Systems and methods for integrating asynchronous signals in distributed antenna system with direct digital interface to base station

ABSTRACT

A distributed antenna system (DAS) includes: signal interface units to receive downlink asynchronous radio carrier signals for radio frequency carriers from external device(s), each having a different clock, the signal interface units configured to: re-clock the downlink asynchronous radio carrier signals to a master clock of the DAS and convert the downlink asynchronous radio carrier signals to downlink digital signals; a host unit communicatively coupled to signal interface units and configured to combine at least two downlink digital signals into an aggregate downlink digital signal; an antenna unit coupled to the host unit and configured to: receive the aggregate downlink digital signal from the host unit, convert the aggregate downlink digital signal(s) and/or another signal based on the aggregate downlink digital signal into downlink radio frequency signals, and wirelessly transmit downlink radio frequency signals to a subscriber unit.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.14/506,441 filed on Oct. 3, 2014 and entitled “SYSTEMS AND METHODS FORINTEGRATING ASYNCHRONOUS SIGNALS IN DISTRIBUTED ANTENNA SYSTEM WITHDIRECT DIGITAL INTERFACE TO BASE STATION”, which claims the benefit ofU.S. Provisional Patent Application Ser. No. 61/887,711 filed on Oct. 7,2013, all of which are hereby incorporated herein by reference.

BACKGROUND

Distributed Antenna Systems (DAS) are used to distribute wireless signalcoverage into buildings or other substantially closed environments. Theantennas are typically connected to a radio frequency (RF) signalsource, such as a service provider's base station. Various methods oftransporting the RF signal from the RF signal source to the antenna havebeen implemented in the art.

SUMMARY

A signal interface unit in a radio system includes an external deviceinterface configured to receive a downlink asynchronous radio carriersignal for a radio frequency carrier from an external device; a clockconversion unit communicatively coupled to the external device interfaceand configured to re-clock the downlink asynchronous radio carriersignal to a master clock of the radio system from the clock of theexternal device; and an antenna side interface configured to communicateat least one of the re-clocked downlink asynchronous radio carriersignal and a downlink digitized radio frequency signal based on there-clocked downlink asynchronous radio carrier signal to an antennaunit.

DRAWINGS

Understanding that the drawings depict only exemplary embodiments andare not therefore to be considered limiting in scope, the exemplaryembodiments will be described with additional specificity and detailthrough the use of the accompanying drawings, in which:

FIG. 1 is a block diagram of an exemplary embodiment of a distributedantenna system;

FIGS. 2A-2D are block diagrams of exemplary embodiments of signalinterface units used in distributed antenna systems, such as theexemplary distributed antenna system in FIG. 1;

FIG. 3 is a block diagrams of exemplary embodiments of an antenna unitused in distributed antenna systems, such as the exemplary distributedantenna system in FIG. 1;

FIGS. 4A-4C are block diagrams of exemplary embodiments of RF conversionmodules used in antenna units of distributed antenna systems, such asthe exemplary antenna unit in FIG. 3;

FIGS. 5A-5B are block diagrams of an exemplary embodiment of an antennaunit used in distributed antenna systems, such as the exemplarydistributed antenna systems in FIG. 1;

FIG. 6 is a flow diagram illustrating one exemplary embodiment of amethod for re-clocking a downlink channelized radio carrier at a signalinterface unit;

FIG. 7 is a flow diagram illustrating one exemplary embodiment of amethod for re-clocking an uplink channelized radio carrier at a signalinterface unit;

FIG. 8 is a flow diagram illustrating one exemplary embodiment of amethod for interfacing a plurality of asynchronous downlink radiocarrier signals in a distributed antenna system;

FIG. 9 is a flow diagram illustrating one exemplary embodiment of amethod for interfacing a plurality of asynchronous uplink radio carriersignals in a distributed antenna system;

FIG. 10 is a flow diagram illustrating one exemplary embodiment of amethod for interfacing a plurality of asynchronous downlink radiocarrier signals at an antenna unit; and

FIG. 11 is a flow diagram illustrating one exemplary embodiment of amethod for interfacing a plurality of asynchronous uplink radio carriersignals at an antenna unit.

In accordance with common practice, the various described features arenot drawn to scale but are drawn to emphasize specific features relevantto the exemplary embodiments. Like reference numbers and designations inthe various drawings indicate like elements.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings that form a part hereof, and in which is shown byway of illustration specific illustrative embodiments. However, it is tobe understood that other embodiments may be utilized and that logical,mechanical, and electrical changes may be made. Furthermore, the methodpresented in the drawing figures and the specification is not to beconstrued as limiting the order in which the individual steps may beperformed. The following detailed description is, therefore, not to betaken in a limiting sense.

Some embodiments described below describe a distributed antenna systemand components within the distributed antenna system including at leastone signal interface unit communicatively coupled to at least oneantenna unit through a distributed switching network. In otherembodiments, the signal interface unit is directly coupled with theantenna unit or is included with the antenna unit in a single device.The signal interface unit is communicatively coupled to at least oneexternal device, such as a base station, through a backhaul network. Inexemplary embodiments, the signal interface unit is at least one of aCommon Public Radio Interface (CPRI) base station interface, an OpenBase Station Architecture Initiative (OBSAI) base station interface, andan Open Radio Interface (ORI) base station interface. The signalinterface acts as a clock conversion unit to convert the clock ofdownlink asynchronous radio carrier signals to a common clock of thesignal interface and/or the distributed antenna system. In exemplaryembodiments, the downlink asynchronous radio carrier signal is a digitalsignal sampled at a particular rate. In exemplary embodiments, thesignal interface unit includes at least one resampling filter thatre-clocks the plurality of downlink asynchronous radio carrier signalsto the master clock of the signal interface unit and/or distributedantenna system 100 from each different clock of each of the plurality ofdownlink asynchronous radio carrier signals. In exemplary embodiments,the signal interface uses interpolation to create a new signal havingthe common clock. In exemplary embodiments, the signal interfaceconverts the downlink asynchronous radio carrier signals from a firstclock domain of the channelized radio carrier base station interface toa second clock domain of the signal interface unit and/or thedistributed antenna system using a Farrow structure. In exemplaryembodiments, the signal interface is configured to re-clock theplurality of downlink asynchronous radio carrier signals by convertingfirst sampling rates of the plurality of channelized radio carriersignals to second sampling rates.

Other embodiments described below describe an antenna unit configured toreceive a plurality of downlink asynchronous digitized radio carriersignals. In exemplary embodiments, the plurality of downlinkasynchronous radio carrier signals are in a digital signal sampled at aparticular rate. The antenna unit includes at least one clock conversionunit for the plurality of downlink asynchronous radio carrier signals.The at least one clock conversion unit converts the clock of thedownlink asynchronous radio carrier signals to a common clock of theantenna unit. In exemplary embodiments, the at least one clockconversion unit includes at least one resampling filter that re-clocksthe plurality of downlink asynchronous radio carrier signals to themaster clock of the remote antenna unit from each different clock ofeach of the plurality of downlink asynchronous radio carrier signals. Inexemplary embodiments, the at least one clock conversion unit usesinterpolation to create a new signal having the common clock. Inexemplary embodiments, the at least one clock conversion unit convertsthe downlink asynchronous radio carrier signals from a first clockdomain of the channelized radio carrier base station interface to asecond clock domain of the remote antenna unit using a Farrow structure.In exemplary embodiments, the at least one clock conversion unit isconfigured to re-clock the plurality of downlink asynchronous radiocarrier signals by converting first sampling rates of the plurality ofchannelized radio carrier signals to second sampling rates.

In exemplary embodiments, the antenna unit is multi-standard and capableof receiving at least one signal and converting it to radio frequency(RF) and transmitting it using at least one antenna. In exemplaryembodiments, the antenna unit is not specific to a number of channels oran air protocol and does not necessarily require any hardware changewhen channels are added or removed, or a new modulation type or airprotocol is used. In exemplary embodiments, a plurality of signalinterface units convert a plurality of external device signals receivedfrom a plurality of external devices and representing individualchannels into a single radio system signal that is transported throughthe distributed switching network to at least one antenna unit thatconverts the single radio system signal into radio frequency (RF)signals and transmits them using at least one antenna. In exemplaryembodiments, the at least one antenna unit includes a single digital toanalog converter and a single RF converter that can up-convert theentire radio system signal into RF spectrum having various channels.

In exemplary embodiments, the external device signals are channelizedsignals. As described herein, channelized signals are specific to aparticular channel. In exemplary embodiments, the channelized signalsare baseband data, such as channelized in-phase (I) and quadrature (Q)data in I/Q pairs. The channelized signals are not positioned relativeto one another and require additional baseband conversion before RFconversion and transmission can be performed. Specifically, if a systemcommunicated the channelized signals to an antenna unit, additionalprocessing would be required at the antenna unit to convert thechannelized signals before RF conversion and transmission.

In contrast, radio system signals are not specific to a particularchannel and may include a number of different channels. The radio systemsignals represent either digitized or analog spectrum and are one stepcloser to RF signals than the channelized signals. In exemplaryembodiments, the radio system signal is at an intermediate frequencythat maps to a large portion of RF spectrum including a number ofchannels. In exemplary embodiments, the radio system signals can simplybe up-converted from the intermediate frequency to radio frequency andtransmitted at an antenna unit as described below. Thus, the antennaunits do not need the capability of processing channelized signalsbefore RF conversion and transmission. Accordingly, in these exemplaryembodiments it doesn't matter what channels are sent to the antennaunits. In exemplary embodiments, the antenna unit communicates withsubscriber units using a first set of channels at first frequencies anda second set of channels at second frequencies. In exemplaryembodiments, the antenna unit communicates using different modulationand/or radio access technologies simultaneously.

FIG. 1 is a block diagram of an exemplary embodiment of a distributedantenna system 100. Distributed antenna system 100 includes at least onesignal interface unit 102 (including signal interface unit 102-1,optional signal interface unit 102-2, and any amount of optional signalinterface units 102 through optional signal interface unit 102-A), atleast one antenna unit 104 (including antenna unit 104-1 and any amountof optional antenna units 104 through optional antenna unit 104-B), andan optional distributed switching network 106.

Each signal interface unit 102 is communicatively coupled to acorresponding external device 108 directly or through a correspondingoptional backhaul network 110. Each external device 108 is configured toprovide signals to be transported through the distributed antenna system100 to each corresponding signal interface unit 102. In the forwardpath, each signal interface unit 102 is configured to receive signalsfrom at least one external device 108. Specifically, signal interfaceunit 102-1 is communicatively coupled to external device 108-1 throughbackhaul network 110-1, optional signal interface unit 102-2 iscommunicatively coupled to optional external device 108-2 throughoptional backhaul network 110-1, and optional signal interface unit102-A is communicatively coupled to optional external device 108-Athrough optional backhaul network 110-1. In exemplary embodiments, theoptional backhaul networks 110 include one or more intermediary devicespositioned between the signal interface unit 102 and its correspondingexternal device 108.

Each signal interface unit 102 is also communicatively coupled to thedistributed switching network 106 across a communication link 112.Specifically, signal interface unit 102-1 is communicatively coupled tothe distributed switching network 106 across communication link 112-1,optional signal interface unit 102-2 is communicatively coupled to thedistributed switching network 106 across communication link 112-2, andoptional signal interface unit 102-A is communicatively coupled to thedistributed switching network 106 across communication link 112-A. Asdescribed in more detail below, each signal interface unit 102 isconfigured to convert signals from the external device 108 to which itis communicatively coupled into a downlink radio system signal andfurther configured to communicate the downlink radio system signal tothe distributed switching network 106 (either directly or through othercomponents of the distributed antenna system 100) across a respectivecommunication link 112.

In exemplary embodiments, each signal interface unit 102 includes aclock conversion unit or functionality to convert the clock of adownlink asynchronous radio carrier signal received from an externaldevice 108 to a common clock of a signal interface unit 102 and/or thedistributed antenna system 100. In exemplary embodiments, the downlinkasynchronous radio carrier signal is a digital signal sampled at aparticular rate. In exemplary embodiments, each signal interface unit102 includes at least one resampling filter that re-clocks the pluralityof downlink asynchronous radio carrier signals received from an externaldevice 108 to the master clock of the signal interface unit 102 and/ordistributed antenna system 100 from each different clock of each of theplurality of downlink asynchronous radio carrier signals received fromeach external device 108. In exemplary embodiments, each signalinterface unit 102 uses interpolation to create a new signal having thecommon clock. In exemplary embodiments, each signal interface unit 102converts the downlink asynchronous radio carrier signals from a firstclock domain of the external device 108 to a second clock domain of thesignal interface unit 102 and/or the distributed antenna system 100using a Farrow structure. In exemplary embodiments, the signal interfaceis configured to re-clock the plurality of downlink asynchronous radiocarrier signals by converting first sampling rates of the plurality ofchannelized radio carrier signals to second sampling rates. In exemplaryembodiments, the external device interface is one of a Common PublicRadio Interface (CPRI) external device interface, an Open Base StationArchitecture Initiative (OBSAI) external device interface, and an OpenRadio Interface (ORI) external device interface.

Similarly in the reverse path, in exemplary embodiments each signalinterface unit 102 is configured to receive uplink radio system signalsacross a respective communication link 112 from distributed switchingnetwork 106. Each signal interface unit 102 is further configured toconvert the received uplink radio system signal to signals formatted forthe associated external device 108 and further configured to communicatethe signals formatted for the associated external device 108 to theassociated external device 108 directly or across the optional backhaulnetwork 110.

In exemplary embodiments, the downlink radio system signals and theuplink radio system signals are I/Q data transported using variousprotocols. In exemplary embodiments, the I/Q data is transported usingone of a Common Public Radio Interface (CPRI) protocol, an Open BaseStation Architecture Initiative (OBSAI) protocol, and an Open RadioInterface (ORI) protocol. In exemplary embodiments, the I/Q data istransported using a wideband (multichannel) radio transport protocol,such as the Serialized RF (SeRF) protocol used by ADCTelecommunications, Inc. (part of TE Connectivity Ltd.) Shakopee, Minn.The SeRF protocol is also described in U.S. patent application Ser. No.11/627,251, assigned to ADC Telecommunications, Inc., published in U.S.Patent Application Publication No. 2008/01101282, and incorporatedherein by reference. In exemplary embodiments, the I/Q data istransported using bit transport protocols, such as Synchronous OpticalNetworking (SONET), Ethernet (including Synchronous Ethernet), etc. Theresampling filters could be used to overcome the asynchronous nature ofthese bit transport protocols that are not phase locked throughout byresampling I/Q data transported using them once it arrives at a signalinterface unit or antenna unit such that it becomes phase locked to thesignal interface unit, distributed antenna system, or antenna unit'sclock.

In exemplary embodiments, each signal interface unit 102 includes aclock conversion unit or functionality to convert the common clock ofthe uplink radio system signal of the distributed antenna system 100 toan uplink asynchronous radio carrier signal having a different clock forcommunication to an external device 108. In exemplary embodiments, theuplink asynchronous radio carrier signal is a digital signal sampled ata particular rate. In exemplary embodiments, each signal interface unit102 includes at least one resampling filter that re-clocks the uplinkradio system signal from the master clock of the signal interface unit102 and/or distributed antenna system 100 to the different clock of theassociated uplink asynchronous radio carrier signal expected by theexternal device 108. In exemplary embodiments, each signal interfaceunit 102 uses interpolation to create a new signal from the signalhaving the common clock. In exemplary embodiments, each signal interfaceunit 102 converts the uplink radio system signal from the second clockdomain of the signal interface unit 102 and/or distributed antennasystem 100 to the first clock domain of the external device 108 using aFarrow structure. In exemplary embodiments, each signal interface unit102 is configured to re-clock the uplink radio system signal byconverting the second sampling rate of the uplink radio system signal toa first sampling rate of the external device 108. In exemplaryembodiments, the external device interface is one of a Common PublicRadio Interface (CPRI) external device interface, an Open Base StationArchitecture Initiative (OBSAI) external device interface, and an OpenRadio Interface (ORI) external device interface.

In exemplary embodiments, optional distributed switching network 106couples the plurality of signal interface units 102 with the at leastone antenna unit 104. In other embodiments, the at least one antennaunit 104 is directly coupled to the at least one signal interface unit102-1. Distributed switching network 106 may include one or moredistributed antenna switches or other components that functionallydistribute downlink radio system signals from the signal interface units102 to the at least one antenna unit 104. Distributed switching network106 also functionally distributes uplink signals from the at least oneantenna unit 104 to the signal interface units 102. In exemplaryembodiments, the distributed switching network 106 can be controlled bya separate controller or another component of the system. In exemplaryembodiments the switching elements of the distributed switching network106 are controlled either manually or automatically. In exemplaryembodiments, the routes can be pre-determined and static. In otherexemplary embodiments, the routes can dynamically change based on timeof day, load, or other factors.

In exemplary embodiments, the downlink radio system signal is a digitalsignal. In exemplary embodiments, the downlink radio system signal is ananalog signal that contains at least one individual channel that ispositioned within a set of spectrum that reflects its eventual locationwithin radio frequency spectrum. Said another way, the channel in eachdownlink radio system signal is at a different frequency than the otherchannels to which it may be aggregated in the distributed switchingnetwork 106. Thus, when multiple downlink radio system signals areaggregated together, the individual channels do not overlap each otherand all channels can be upconverted together to radio frequency spectrumsimultaneously. In exemplary embodiments, the downlink radio systemsignal is a digital signal through some of the distributed switchingnetwork and is converted to an analog signal at an intermediary devicepositioned within the distributed switching network.

Each antenna unit 104 is communicatively coupled to the distributedswitching network 106 across a communication link 114. Specifically,antenna unit 104-1 is communicatively coupled to the distributedswitching network 106 across communication link 114-1 and optionalantenna unit 104-B is communicatively coupled to the distributedswitching network 106 across communication link 114-B. In exemplaryembodiments, some or all of the antenna units 104 receive a singledownlink radio system signal from the distributed switching network 106or directly from a signal interface unit 102. In exemplary embodiments,some or all of the antenna units 104 include components configured forextracting at least one downlink radio system signal from an aggregatedownlink radio system signal and components configured for aggregatingat least one uplink radio system signal into an aggregate uplink radiosystem signal as well as at least one radio frequency converterconfigured to convert between at least one radio system signal and atleast one radio frequency band and at least one radio frequency antenna116 configured to transmit and receive signals in the at least one radiofrequency band to at least one subscriber unit 118. In exemplaryembodiments, the downlink radio system signal is an aggregate ofmultiple downlink radio system signals each with a channel positionedwithin a set of spectrum that reflects its location within the RFspectrum. In exemplary embodiments having multiple downlink radio systemsignals aggregated together, the individual channels can be converted tothe at least one radio frequency band signals simultaneously.

In the downstream, each antenna unit 104 is configured to extract atleast one downlink radio system signal from the downlink aggregate radiosystem signal. Each antenna unit 104 is further configured to convertthe at least one downlink radio system signal into a downlink radiofrequency (RF) signal in a radio frequency band. In exemplaryembodiments, this may include digital to analog converters andoscillators. Each antenna unit 104 is further configured to transmit thedownlink radio frequency signal in the radio frequency band to at leastone subscriber unit using at least one radio frequency antenna 116. In aspecific exemplary embodiment, antenna unit 104-1 is configured toextract at least one downlink radio system signal from the downlinkaggregate radio system signal received from the distributed switchingnetwork 106 and further configured to convert the at least one downlinkradio system signal into a downlink radio frequency signal in a radiofrequency band. Antenna unit 104-1 is further configured to transmit thedownlink radio frequency signal in a radio frequency band using a radiofrequency antenna 116-1 to at least one subscriber unit 118-1. Inexemplary embodiments, antenna unit 104-1 is configured to extract aplurality of downlink radio system signals from the downlink aggregateradio system signal received from the distributed switching network 106and configured to convert the plurality of downlink radio system signalsto a plurality of downlink radio frequency signals. In exemplaryembodiments with a plurality of radio frequency signals, the antennaunit 104-1 is further configured to transmit the downlink radiofrequency signal in at least one radio frequency band to at least onesubscriber unit 118-1 using at least radio frequency antenna 116-1. Inexemplary embodiments, the antenna unit 104-1 is configured to transmitone downlink radio frequency signal to one subscriber unit 118-1 using aradio frequency antenna 116-1 and another radio frequency signal toanother subscriber unit 118-D using another radio frequency antenna116-C. In exemplary embodiments, other combinations of radio frequencyantennas 116 and other components are used to communicate othercombinations of radio frequency signals in other various radio frequencybands to various subscriber units 118, such as but not limited to usingmultiple antenna to communicate with a single subscriber unit 118.

Similarly in the reverse path, in exemplary embodiments each antennaunit 104 is configured to receive uplink radio frequency signals from atleast one subscriber unit 118 using at least one radio frequency antenna116. Each antenna unit 104 is further configured to convert the radiofrequency signals to at least one uplink radio system signal. Eachantenna unit 104 is further configured to aggregate the at least oneuplink radio system signal into an aggregate uplink radio system signaland further configured to communicate the aggregate uplink radio systemsignal across at least one communication link 114 to the distributedswitching network 106. In exemplary embodiments, antenna units 104multiplex uplink signals in different bands onto the same interface forcommunication to the next upstream element. In other exemplaryembodiments (such as example embodiments implementing diversityprocessing), the antenna unit 104 could aggregate (i.e. sum/combine)uplink signals in an intelligent manner. In exemplary embodiments, eachuplink radio system signal contains a channel that is positioned withina set of spectrum that reflects its location within the RF spectrum.Thus and even though the uplink radio system signals that are aggregatedwill overlap in frequency spectrum, the individual channels themselvesfrom the aggregated uplink radio system signals do not overlap eachother when multiple uplink radio system signals are aggregated together.

In exemplary embodiments, the entire distributed antenna system 100 isphase locked using a master clock provided by at least one componentwithin the distributed antenna system, such as a signal interface unit102, an antenna unit 104, or another intermediary component within thedistributed switching network 106 (such as a host unit for thedistributed antenna system). Accordingly, once the asynchronous signalsreceived from the external devices 108 have been re-clocked to themaster clock of the distributed antenna system 100, these signals arephase locked through the distributed antenna system using the commonmaster clock of the distributed antenna system 100.

In exemplary embodiments, a master reference clock is distributedbetween the various components of the distributed antenna system 100 tokeep the various components locked to the same clock. While there-clocking at the signal interface units 102 described herein enablesasynchronous signals having different rates to be received at differentsignal interface units 102 and be converted to a common clock, in someembodiments the master reference clock to at least some of the externaldevices 108 are tied with the distributed antenna system 100. Inexemplary embodiments, a master reference clock is provided to at leastone external device 108 via at least one signal interface unit 102 sothat the external device 108 can lock to the master reference clock aswell. In other exemplary embodiments, the master reference clock isprovided from at least one external device 108 to the distributedantenna system 100 via at least one signal interface unit 102. Inexemplary embodiments, the master reference clock is generated within acomponent of the distributed antenna system 100, such as a signalinterface unit 102, an antenna unit 104, or somewhere within thedistributed switching network 106.

In exemplary embodiments, the communication links 112 and/or thecommunication links 114 are optical fibers and the communication acrossthe communication links 112 and/or the communication links 114 isoptical. In these embodiments, an electrical to optical conversionoccurs at the antenna units 104 and/or at an intermediary device withinthe optional distributed switching network 106. In other embodiments,the communication links 112 and/or the communication links 114 areconductive cables (such as coaxial cable, twisted pair, etc.) and thecommunication across the communication links 112 and/or thecommunication links 114 is electrical. In exemplary embodiments, thecommunication across the communication links 112 and/or thecommunication links 114 is digital. In exemplary embodiments, thecommunication across the communication links 112 and/or thecommunication links 114 is analog. In exemplary embodiments, any mixtureof optical, electrical, analog, and digital communication occurs acrossthe communication links 112 and the communication links 114. Inexemplary embodiments, an antenna unit 104 may include functionality toconvert between digital and analog signals.

FIGS. 2A-2D are block diagrams of exemplary embodiments of signalinterface units 102 used in distributed antenna systems, such as theexemplary distributed antenna system 100 described above. Each of FIGS.2A-2D illustrates a different embodiment of a type of signal interfaceunit 102, labeled 102A-102D respectively.

FIG. 2A is a block diagram of an exemplary embodiment of a signalinterface unit 102, general signal interface unit 102A. General signalinterface unit 102A includes clock conversion module 202, signalconversion module 204, external device interface 206A, antenna sideinterface 208, optional processor 210, optional memory 212, and optionalpower supply 214. In exemplary embodiments, signal conversion module 204is communicatively coupled to an external device 108A through theexternal device interface 206A. Signal conversion module 204 is alsocommunicatively coupled to at least one communication link 112 byantenna side interface 208. In exemplary embodiments, the communicationlink 112 is an optical communication link across a fiber optic cable,though it can also be other types of wired or wireless links in otherembodiments. In exemplary embodiments, the signal conversion module 204and/or portions of the external device interface 206A and/or the antennaside interface 208 are implemented using optional processor 210 andoptional memory 212. In exemplary embodiments, the optional power supply214 provides power to the various elements of the signal interface unit102A.

In the downlink, the external device interface 206A is configured toreceive downlink external device signals from the external device 108A.The clock conversion module 202 is configured to convert the clock of adownlink external device signal received from an external device 108A toa common clock of the general signal interface unit 102A and/or thedistributed antenna system 100. In exemplary embodiments, the clockconversion module 202 includes at least one resampling filter thatre-clocks the downlink external device signal received from the externaldevice 108A to the master clock of the general signal interface unit102A and/or distributed antenna system 100 from the different clock ofthe downlink external device signal received from the external device108A. In exemplary embodiments, the at least one clock conversion module202 uses interpolation to create a new signal having the common clock.In exemplary embodiments, the clock conversion module 202 converts thedownlink external device signal from a first clock domain of theexternal device 108A to a second clock domain of the general signalinterface unit 102A and/or the distributed antenna system 100 using aFarrow structure. In exemplary embodiments, the clock conversion module202 is configured to re-clock the downlink external device signal byconverting a first sampling rate of the downlink external device signalto a second sampling rate. In exemplary embodiments, the external deviceinterface 206A is one of a Common Public Radio Interface (CPRI) externaldevice interface, an Open Base Station Architecture Initiative (OBSAI)external device interface, and an Open Radio Interface (ORI) externaldevice interface.

The signal conversion module 204 is configured to convert the receiveddownlink external device signals to a downlink radio system signal. Inexemplary embodiments, the signal conversion module 204 and/or theantenna side interface 208 converts the radio system signal fromelectrical signals to optical signals for output on communication link112. In other embodiments, the radio system signal is transported usinga conductive communication medium, such as coaxial cable or twistedpair, and the optical conversion is not necessary. The antenna sideinterface 208 is configured to communicate the downlink radio systemsignal on communication link 112.

In exemplary embodiments, the downlink radio system signal is specificto a particular channel and requires additional baseband conversionbefore radio frequency conversion and transmission can be performed. Inexemplary embodiments, the downlink radio system signal is not specificto a particular channel and does not require additional basebandconversion before radio frequency conversion and transmission can beperformed. In exemplary embodiments, the downlink radio system signalcontains an individual channel that is positioned within a set ofspectrum that reflects its eventual location within radio frequencyspectrum. In exemplary embodiments, the downlink radio system signalinterface is communicatively coupled with an intermediary device thataggregates the downlink radio system signal with at least one otherdownlink radio system signal before being transmitted to at least oneantenna unit 104. In exemplary embodiments, the individual channelswithin the downlink radio system signal and the at least one otherdownlink radio system signal do not overlap and can be upconvertedtogether simultaneously to radio frequency spectrum.

In the uplink, antenna side interface 208 is configured to receive anuplink radio system signal from communication link 112. In exemplaryembodiments where communication link 112 is an optical medium, theantenna side interface 208 and/or the signal conversion module 204 isconfigured to convert the uplink radio system signal between receivedoptical signals and electrical signals. In other embodiments, the radiosystem signal is transported using a conductive communication medium,such as coaxial cable or twisted pair, and the optical conversion is notnecessary. The signal conversion module 204 is further configured toconvert the uplink radio system signal to uplink signals.

In exemplary embodiments, the downlink radio system signals and theuplink radio system signals are I/Q data transported using variousprotocols. In exemplary embodiments, the I/Q data is transported usingone of a Common Public Radio Interface (CPRI) protocol, an Open BaseStation Architecture Initiative (OBSAI) protocol, and an Open RadioInterface (ORI) protocol. In exemplary embodiments, the I/Q data istransported using a wideband (multichannel) radio transport protocol,such as the Serialized RF (SeRF) protocol used by ADCTelecommunications, Inc. (part of TE Connectivity Ltd.) Shakopee, Minn.The SeRF protocol is also described in U.S. patent application Ser. No.11/627,251, assigned to ADC Telecommunications, Inc., published in U.S.Patent Application Publication No. 2008/01101282, and incorporatedherein by reference. In exemplary embodiments, the I/Q data istransported using bit transport protocols, such as Synchronous OpticalNetworking (SONET), Ethernet (including Synchronous Ethernet), etc. Theresampling filters could be used to overcome the asynchronous nature ofthese bit transport protocols that are not phase locked throughout byresampling I/Q data transported using them once it arrives at a generalsignal interface unit 102A or antenna unit 104 such that it becomesphase locked to the general signal interface unit 102A, distributedantenna system 100, or antenna unit 104's clock.

In exemplary embodiments, the clock conversion module 202 converts thecommon clock of the uplink radio system signal of the distributedantenna system 100 to an uplink external device signal having adifferent clock for communication to an external device 108A. Inexemplary embodiments, the clock conversion module 202 includes at leastone resampling filter that re-clocks the uplink radio system signal fromthe master clock of the signal interface unit 102 and/or distributedantenna system 100 to the different clock of the associated uplinkexternal device signal expected by the external device 108A. Inexemplary embodiments, the clock conversion module 202 usesinterpolation to create a new signal from the signal having the commonclock. In exemplary embodiments, the clock conversion module 202converts the uplink radio system signal from the second clock domain ofthe signal interface unit 102 and/or distributed antenna system 100 tothe first clock domain of the external device 108A using a Farrowstructure. In exemplary embodiments, the clock conversion module 202 isconfigured to re-clock the uplink radio system signal by converting thesecond sampling rate of the uplink radio system signal to a firstsampling rate of the uplink external device signal expected by theexternal device 108A. External device interface 206A is configured tocommunicate the uplink external device signal to the external device108A. In exemplary embodiments, the external device interface 206A isone of a Common Public Radio Interface (CPRI) external device interface,an Open Base Station Architecture Initiative (OBSAI) external deviceinterface, and an Open Radio Interface (ORI) external device interface.

In exemplary embodiments, the uplink radio system signal contains anindividual channel that is positioned within a set of spectrum thatreflects its previous location within radio frequency spectrum. Inexemplary embodiments, the general signal interface unit 102A iscommunicatively coupled with an intermediary device that separates theuplink radio system signal from an aggregate uplink radio system signalreceived from at least one antenna unit 104 and including at least oneother uplink radio system signal. In exemplary implementations, theindividual channels within the uplink radio system signal and the atleast one other uplink radio system signal do not overlap and can bedownconverted together simultaneously from radio frequency spectrum. Inexemplary embodiments, the uplink radio system signal is not specific toa particular channel and does not require any baseband processing whenconverted from radio frequency, while the uplink data may be specific toa particular channel and require baseband processing when beingconverted from radio frequency.

In exemplary embodiments, an optional signal interface unit clock unitis communicatively coupled to an external device clock unit of theexternal device 108A. In exemplary embodiments, a master reference clockis provided to the external device clock unit of the external device108A from the signal interface unit clock unit of the signal interfaceunit 102A. In other exemplary embodiments, a master reference clock isprovided from the external device clock unit of the external device 108Ato the signal interface unit clock unit of the signal interface unit102A. In other exemplary embodiments, a network interface clock unit isnot coupled directly to an external device clock unit of the externaldevice 108A to provide the master reference clock to the externaldevice. Instead, a signal interface unit clock unit provides the masterreference clock to the signal conversion module 204 and the masterreference clock is embedded in an upstream signal from the externaldevice interface 206A to the external device 108A. In particular, uplinksignals can be clocked using the master clock, such that the masterclock is embedded in the uplink signals. Then, an external device clockunit extracts the master clock from uplink signals and distributes themaster clock as appropriate in the external device 108A to establish acommon clock with the distributed antenna system in the external device108A. In exemplary embodiments where the master reference clock isprovided from an external device 108A to the distributed antenna system100, the master reference clock can be embedded in the downlink externaldevice signals by an external device clock unit so that the downlinkexternal device signals communicated from the external device 108A tothe external device interface 206A can be extracted by a signalinterface unit clock unit and distributed as appropriate within thesignal interface unit 102A and the distributed antenna system 100generally.

FIG. 2B is a block diagram of an exemplary embodiment of a type ofsignal interface unit 102, channelized radio carrier signal interfaceunit 102B. Channelized radio carrier signal interface unit 102B includesa clock conversion module 202, a signal conversion module 204, achannelized radio carrier external device interface 206B, the antennaside interface 208, the optional processor 210, the optional memory 212,and the optional power supply 214. Channelized radio carrier signalinterface unit 102B includes similar components to general signalinterface unit 102A and operates according to similar principles andmethods as general signal interface unit 102A. The difference betweenchannelized radio carrier signal interface unit 102B and general signalinterface unit 102A is that the channelized radio carrier signalinterface unit 102B is a more specific embodiment that interfaces with achannelized radio carrier base station unit 108B using a channelizedradio carrier external device interface 206B. Further, the channelizedradio carrier signal interface unit 102B includes a signal conversionmodule 204 that converts between channelized radio carrier signals andthe radio system signals used for transport in the distributed antennasystem 100.

In the downlink, the channelized radio carrier external device interface206B is configured to receive a downlink channelized radio carriersignal from the channelized radio carrier base station unit 108B. Theclock conversion module 202 is configured to convert the clock of thedownlink channelized radio carrier signal received from the channelizedradio carrier base station unit 108B to a common clock of thechannelized radio carrier signal interface unit 102B and/or thedistributed antenna system 100. In exemplary embodiments, the clockconversion module 202 includes at least one resampling filter thatre-clocks the downlink channelized radio carrier signal received fromthe channelized radio carrier base station unit 108B to the master clockof the channelized radio carrier signal interface unit 102B and/ordistributed antenna system 100 from the different clock of the downlinkchannelized radio carrier signal received from the channelized radiocarrier base station unit 108B. In exemplary embodiments, the clockconversion module 202 converts the downlink channelized radio carriersignal from a first clock domain of the channelized radio carrier basestation unit 108B to a second clock domain of the channelized radiocarrier signal interface unit 102B and/or the distributed antenna system100 using a Farrow structure. In exemplary embodiments, the clockconversion module 202 is configured to re-clock the downlink channelizedradio carrier signal by converting a first sampling rate of the downlinkchannelized radio carrier signal to a second sampling rate. In exemplaryembodiments, the channelized radio carrier signal interface unit 102B isone of a Common Public Radio Interface (CPRI) external device interface,an Open Base Station Architecture Initiative (OBSAI) external deviceinterface, and an Open Radio Interface (ORI) external device interface.

The signal conversion module 204 is configured to convert the receiveddownlink channelized radio carrier signals to a downlink radio systemsignal. In exemplary embodiments, the signal conversion module 204and/or the antenna side interface 208 converts the radio system signalfrom electrical signals to optical signals for output on communicationlink 112. In other embodiments, the radio system signal is transportedusing a conductive communication medium, such as coaxial cable ortwisted pair, and the optical conversion is not necessary. The antennaside interface 208 is configured to communicate the downlink radiosystem signal on communication link 112.

In the uplink, antenna side interface 208 is configured to receive anuplink radio system signal from communication link 112. In exemplaryembodiments where communication link 112 is an optical medium, theantenna side interface 208 and/or the signal conversion module 204 isconfigured to convert the uplink radio system signal between receivedoptical signals and electrical signals. In other embodiments, the radiosystem signal is transported using a conductive communication medium,such as coaxial cable or twisted pair, and the optical conversion is notnecessary. The signal conversion module 204 is further configured toconvert the uplink radio system signal to uplink channelized radiocarrier signals.

In exemplary embodiments, the downlink channelized radio carrier data isspecific to a particular channel and requires additional channelizedradio carrier conversion before radio frequency conversion andtransmission can be performed. In exemplary embodiments, the downlinkradio system signals and the uplink radio system signals are I/Q datatransported using various protocols. In exemplary embodiments, the I/Qdata is transported using one of a Common Public Radio Interface (CPRI)protocol, an Open Base Station Architecture Initiative (OBSAI) protocol,and an Open Radio Interface (ORI) protocol. In exemplary embodiments,the I/Q data is transported using a wideband (multichannel) radiotransport protocol, such as the Serialized RF (SeRF) protocol used byADC Telecommunications, Inc. (part of TE Connectivity Ltd.) Shakopee,Minn. The SeRF protocol is also described in U.S. patent applicationSer. No. 11/627,251, assigned to ADC Telecommunications, Inc., publishedin U.S. Patent Application Publication No. 2008/01101282, andincorporated herein by reference. In exemplary embodiments, the I/Q datais transported using bit transport protocols, such as SynchronousOptical Networking (SONET), Ethernet (including Synchronous Ethernet),etc. The resampling filters could be used to overcome the asynchronousnature of these bit transport protocols that are not phase lockedthroughout by resampling I/Q data transported using them once it arrivesat a channelized radio carrier signal interface unit 102B or antennaunit 104 such that it becomes phase locked to the channelized radiocarrier signal interface unit 102B, distributed antenna system 100, orantenna unit 104's clock.

In exemplary embodiments, the clock conversion module 202 converts thecommon clock of the uplink radio system signal of the distributedantenna system 100 to an uplink channelized radio carrier base stationunit signal having a different clock for communication to thechannelized radio carrier base station unit 108B. In exemplaryembodiments, the clock conversion module 202 includes at least oneresampling filter that re-clocks the uplink radio system signal from themaster clock of the channelized radio carrier signal interface unit 102Band/or distributed antenna system 100 to the different clock of theassociated uplink channelized radio carrier base station unit signalexpected by the channelized radio carrier base station unit 108B. Inexemplary embodiments, the clock conversion module 202 usesinterpolation to create a new signal from the signal having the commonclock. In exemplary embodiments, the clock conversion module 202converts the uplink radio system signal from the second clock domain ofthe channelized radio carrier signal interface unit 102B and/ordistributed antenna system 100 to the first clock domain of thechannelized radio carrier base station unit 108B using a Farrowstructure. In exemplary embodiments, the clock conversion module 202 isconfigured to re-clock the uplink radio system signal by converting thesecond sampling rate of the uplink radio system signal to a firstsampling rate of the uplink channelized radio carrier base station unitsignal expected by the channelized radio carrier base station unit 108B.Channelized radio carrier external device interface 206B is configuredto communicate the uplink channelized radio carrier base station unitsignal to the channelized radio carrier base station unit 108B. Inexemplary embodiments, the channelized radio carrier external deviceinterface 206B is one of a Common Public Radio Interface (CPRI) externaldevice interface, an Open Base Station Architecture Initiative (OBSAI)external device interface, and an Open Radio Interface (ORI) externaldevice interface. Channelized radio carrier external device interface206B is configured to communicate the uplink channelized radio carriersignals to the channelized radio carrier base station unit 108B.

In exemplary embodiments, the uplink radio system signal contains anindividual channel that is positioned within a set of spectrum thatreflects its eventual location within radio frequency spectrum. Inexemplary embodiments, the channelized radio carrier signal interfaceunit 102B is communicatively coupled with an intermediary device thatseparates the uplink radio system signal from an aggregate uplink radiosystem signal received from at least one antenna unit 104 and includingat least one other uplink radio system signal. In exemplaryimplementations, the individual channels within the uplink radio systemsignal and the at least one other uplink radio system signal do notoverlap and can be downconverted together simultaneously from radiofrequency spectrum. In exemplary embodiments, uplink channelized data isspecific to a particular channel and requires channelized radio carrierprocessing when being converted from radio frequency.

In exemplary embodiments, an optional network interface clock unit iscommunicatively coupled to an external device clock unit of thechannelized radio carrier base station unit 108B and a master referenceclock is provided as described above with reference to FIG. 2A.

FIG. 2C is a block diagram of an exemplary embodiment of a type ofsignal interface unit 102, baseband signal interface unit 102C. Basebandsignal interface unit 102C includes a clock conversion module 202, asignal conversion module 204, a baseband external device interface 206C,the antenna side interface 208, the optional processor 210, the optionalmemory 212, and the optional power supply 214. Baseband signal interfaceunit 102C includes similar components to general signal interface unit102A and operates according to similar principles and methods as generalsignal interface unit 102A. The difference between baseband signalinterface unit 102C and general signal interface unit 102A is that thebaseband signal interface unit 102C is a more specific embodiment thatinterfaces with a baseband base station 108C using a baseband externaldevice interface 206C. Further the baseband signal interface unit 102Cincludes a signal conversion module 204 that converts between basebandsignals and the radio system signals used for transport in thedistributed antenna system 100.

In the downlink, the baseband external device interface 206C isconfigured to receive a downlink baseband signal from the baseband basestation 108C. The clock conversion module 202 is configured to convertthe clock of the downlink baseband signal received from the basebandbase station 108C to a common clock of the baseband signal interfaceunit 102C and/or the distributed antenna system 100. In exemplaryembodiments, the clock conversion module 202 includes at least oneresampling filter that re-clocks the downlink baseband signal receivedfrom the baseband base station 108C to the master clock of the basebandsignal interface unit 102C and/or distributed antenna system 100 fromthe different clock of the downlink baseband signal received from thebaseband base station 108C. In exemplary embodiments, the clockconversion module 202 converts the downlink baseband signal from a firstclock domain of the baseband base station 108C to a second clock domainof the baseband signal interface unit 102C and/or the distributedantenna system 100 using a Farrow structure. In exemplary embodiments,the clock conversion module 202 is configured to re-clock the downlinkbaseband signal by converting a first sampling rate of the downlinkbaseband signal to a second sampling rate. In exemplary embodiments, thebaseband signal interface unit 102C is one of a Common Public RadioInterface (CPRI) external device interface, an Open Base StationArchitecture Initiative (OBSAI) external device interface, and an OpenRadio Interface (ORI) external device interface.

The signal conversion module 204 is configured to convert the receiveddownlink baseband signals to a downlink radio system signal. Inexemplary embodiments, the signal conversion module 204 and/or theantenna side interface 208 converts the radio system signal fromelectrical signals to optical signals for output on communication link112. In other embodiments, the radio system signal is transported usinga conductive communication medium, such as coaxial cable or twistedpair, and the optical conversion is not necessary. The antenna sideinterface 208 is configured to communicate the downlink radio systemsignal on communication link 112.

In the uplink, antenna side interface 208 is configured to receive anuplink radio system signal from communication link 112. In exemplaryembodiments where communication link 112 is an optical medium, theantenna side interface 208 and/or the signal conversion module 204 isconfigured to convert the uplink radio system signal between receivedoptical signals and electrical signals. In other embodiments, the radiosystem signal is transported using a conductive communication medium,such as coaxial cable or twisted pair, and the optical conversion is notnecessary. The signal conversion module 204 is further configured toconvert the uplink radio system signal to uplink baseband signals.

In exemplary embodiments, the downlink baseband data is specific to aparticular channel and requires additional baseband conversion beforeradio frequency conversion and transmission can be performed. Inexemplary embodiments, the downlink radio system signals and the uplinkradio system signals are I/Q data transported using various protocols.In exemplary embodiments, the I/Q data is transported using one of aCommon Public Radio Interface (CPRI) protocol, an Open Base StationArchitecture Initiative (OBSAI) protocol, and an Open Radio Interface(ORI) protocol. In exemplary embodiments, the I/Q data is transportedusing a wideband (multichannel) radio transport protocol, such as theSerialized RF (SeRF) protocol used by ADC Telecommunications, Inc. (partof TE Connectivity Ltd.) Shakopee, Minn. The SeRF protocol is alsodescribed in U.S. patent application Ser. No. 11/627,251, assigned toADC Telecommunications, Inc., published in U.S. Patent ApplicationPublication No. 2008/01101282, and incorporated herein by reference. Inexemplary embodiments, the I/Q data is transported using bit transportprotocols, such as Synchronous Optical Networking (SONET), Ethernet(including Synchronous Ethernet), etc. The resampling filters could beused to overcome the asynchronous nature of these bit transportprotocols that are not phase locked throughout by resampling I/Q datatransported using them once it arrives at a baseband signal interfaceunit 102C or antenna unit 104 such that it becomes phase locked to thebaseband signal interface unit 102C, distributed antenna system 100, orantenna unit 104's clock.

In exemplary embodiments, the clock conversion module 202 converts thecommon clock of the uplink radio system signal of the distributedantenna system 100 to an uplink baseband base station signal having adifferent clock for communication to the baseband base station 108C. Inexemplary embodiments, the clock conversion module 202 includes at leastone resampling filter that re-clocks the uplink radio system signal fromthe master clock of the baseband signal interface unit 102C and/ordistributed antenna system 100 to the different clock of the associateduplink baseband base station signal expected by the baseband basestation 108C. In exemplary embodiments, the clock conversion module 202uses interpolation to create a new signal from the signal having thecommon clock. In exemplary embodiments, the clock conversion module 202converts the uplink radio system signal from the second clock domain ofthe baseband signal interface unit 102C and/or distributed antennasystem 100 to the first clock domain of the baseband base station 108Cusing a Farrow structure. In exemplary embodiments, the clock conversionmodule 202 is configured to re-clock the uplink radio system signal byconverting the second sampling rate of the uplink radio system signal toa first sampling rate of the uplink baseband base station signalexpected by the baseband base station 108C. Baseband external deviceinterface 206C is configured to communicate the uplink baseband basestation signal to the baseband base station 108C. In exemplaryembodiments, the baseband external device interface 206C is one of aCommon Public Radio Interface (CPRI) external device interface, an OpenBase Station Architecture Initiative (OBSAI) external device interface,and an Open Radio Interface (ORI) external device interface. Basebandexternal device interface 206C is configured to communicate the uplinkbaseband signals to the baseband base station 108C.

In exemplary embodiments, the uplink radio system signal contains anindividual channel that is positioned within a set of spectrum thatreflects its eventual location within radio frequency spectrum. Inexemplary embodiments, the baseband signal interface unit 102C iscommunicatively coupled with an intermediary device that separates theuplink radio system signal from an aggregate uplink radio system signalreceived from at least one antenna unit 104 and including at least oneother uplink radio system signal. In exemplary implementations, theindividual channels within the uplink radio system signal and the atleast one other uplink radio system signal do not overlap and can bedownconverted together simultaneously from radio frequency spectrum. Inexemplary embodiments, uplink channelized data is specific to aparticular channel and requires baseband processing when being convertedfrom radio frequency.

In exemplary embodiments, an optional network interface clock unit iscommunicatively coupled to an external device clock unit of the basebandbase station 108C and a master reference clock is provided as describedabove with reference to FIG. 2A.

FIG. 2D is a block diagram of an exemplary embodiment of a type ofsignal interface unit 102, Common Public Radio Interface (CPRI) signalinterface unit 102D. CPRI signal interface unit 102D includes a clockconversion module 202, a signal conversion module 204, a CPRI externaldevice interface 206D, the antenna side interface 208, the optionalprocessor 210, the optional memory 212, and the optional power supply214. CPRI signal interface unit 102D includes similar components togeneral signal interface unit 102A and operates according to similarprinciples and methods as general signal interface unit 102A. Thedifference between CPRI signal interface unit 102D and general signalinterface unit 102A is that the CPRI signal interface unit 102D is amore specific embodiment that interfaces with a CPRI base station 108Dusing a CPRI external device interface 206D. Further, the CPRI signalinterface unit 102D includes a signal conversion module 204 thatconverts between CPRI signals and the radio system signals used fortransport in the distributed antenna system 100.

In the downlink, the CPRI external device interface 206D is configuredto receive a downlink CPRI signal from the CPRI base station 108D. Theclock conversion module 202 is configured to convert the clock of thedownlink CPRI signal received from the CPRI base station 108D to acommon clock of the CPRI signal interface unit 102D and/or thedistributed antenna system 100. In exemplary embodiments, the clockconversion module 202 includes at least one resampling filter thatre-clocks the downlink CPRI signal received from the CPRI base station108D to the master clock of the CPRI signal interface unit 102D and/ordistributed antenna system 100 from the different clock of the downlinkCPRI signal received from the CPRI base station 108D. In exemplaryembodiments, the clock conversion module 202 uses interpolation tocreate a new signal having the common clock. In exemplary embodiments,the clock conversion module 202 converts the downlink CPRI signal from afirst clock domain of the CPRI base station 108D to a second clockdomain of the CPRI signal interface unit 102D and/or the distributedantenna system 100 using a Farrow structure. In exemplary embodiments,the clock conversion module 202 is configured to re-clock the downlinkCPRI signal by converting a first sampling rate of the downlink CPRIsignal to a second sampling rate.

The signal conversion module 204 is configured to convert the receiveddownlink CPRI signals to a downlink radio system signal. In exemplaryembodiments, the signal conversion module 204 and/or the antenna sideinterface 208 converts the radio system signal from electrical signalsto optical signals for output on communication link 112. In otherembodiments, the radio system signal is transported using a conductivecommunication medium, such as coaxial cable or twisted pair, and theoptical conversion is not necessary. The antenna side interface 208 isconfigured to communicate the downlink radio system signal oncommunication link 112.

In exemplary embodiments, the downlink baseband data is specific to aparticular channel and requires additional baseband conversion beforeradio frequency conversion and transmission can be performed. Inexemplary embodiments, the downlink radio system signal is not specificto a particular channel and does not require additional basebandconversion before radio frequency conversion and transmission can beperformed. In exemplary embodiments, the downlink radio system signalcontains an individual channel that is positioned within a set ofspectrum that reflects its eventual location within radio frequencyspectrum. In exemplary embodiments, the downlink radio system signalinterface is communicatively coupled with an intermediary device thataggregates the downlink radio system signal with at least one otherdownlink radio system signal before being transmitted to at least oneantenna unit 104. In exemplary embodiments, the individual channelswithin the downlink radio system signal and the at least one otherdownlink radio system signal do not overlap and can be upconvertedtogether simultaneously to radio frequency spectrum.

In the uplink, antenna side interface 208 is configured to receive anuplink radio system signal from communication link 112. In exemplaryembodiments where communication link 112 is an optical medium, theantenna side interface 208 and/or the signal conversion module 204 isconfigured to convert the uplink radio system signal between receivedoptical signals and electrical signals. In other embodiments, the radiosystem signal is transported using a conductive communication medium,such as coaxial cable or twisted pair, and the optical conversion is notnecessary. The signal conversion module 204 is further configured toconvert the uplink radio system signal to uplink CPRI signals.

In exemplary embodiments, the downlink radio system signals and theuplink radio system signals are I/Q data transported using variousprotocols. In exemplary embodiments, the I/Q data is transported usingone of a Common Public Radio Interface (CPRI) protocol, an Open BaseStation Architecture Initiative (OBSAI) protocol, and an Open RadioInterface (ORI) protocol. In exemplary embodiments, the I/Q data istransported using a wideband (multichannel) radio transport protocol,such as the Serialized RF (SeRF) protocol used by ADCTelecommunications, Inc. (part of TE Connectivity Ltd.) Shakopee, Minn.The SeRF protocol is also described in U.S. patent application Ser. No.11/627,251, assigned to ADC Telecommunications, Inc., published in U.S.Patent Application Publication No. 2008/01101282, and incorporatedherein by reference. In exemplary embodiments, the I/Q data istransported using bit transport protocols, such as Synchronous OpticalNetworking (SONET), Ethernet (including Synchronous Ethernet), etc. Theresampling filters could be used to overcome the asynchronous nature ofthese bit transport protocols that are not phase locked throughout byresampling I/Q data transported using them once it arrives at a CPRIsignal interface unit 102D or antenna unit 104 such that it becomesphase locked to the CPRI signal interface unit 102D, distributed antennasystem 100, or antenna unit 104's clock.

In exemplary embodiments, the clock conversion module 202 converts thecommon clock of the uplink radio system signal of the distributedantenna system 100 to an uplink CPRI base station signal having adifferent clock for communication to the CPRI base station 108D. Inexemplary embodiments, the clock conversion module 202 includes at leastone resampling filter that re-clocks the uplink radio system signal fromthe master clock of the CPRI signal interface unit 102D and/ordistributed antenna system 100 to the different clock of the associateduplink CPRI base station signal expected by the CPRI base station 108D.In exemplary embodiments, the clock conversion module 202 usesinterpolation to create a new signal from the signal having the commonclock. In exemplary embodiments, the clock conversion module 202converts the uplink radio system signal from the second clock domain ofthe CPRI signal interface unit 102D and/or distributed antenna system100 to the first clock domain of the CPRI base station 108D using aFarrow structure. In exemplary embodiments, the clock conversion module202 is configured to re-clock the uplink radio system signal byconverting the second sampling rate of the uplink radio system signal toa first sampling rate of the uplink CPRI base station signal expected bythe CPRI base station 108D. CPRI external device interface 206D isconfigured to communicate the uplink CPRI base station signal to theCPRI base station 108D. CPRI external device interface 206D isconfigured to communicate the uplink CPRI signals to the CPRI basestation 108D.

In exemplary embodiments, the uplink radio system signal contains anindividual channel that is positioned within a set of spectrum thatreflects its eventual location within radio frequency spectrum. Inexemplary embodiments, the CPRI signal interface unit 102D iscommunicatively coupled with an intermediary device that separates theuplink radio system signal from an aggregate uplink radio system signalreceived from at least one antenna unit 104 and including at least oneother uplink radio system signal. In exemplary implementations, theindividual channels within the uplink radio system signal and the atleast one other uplink radio system signal do not overlap and can bedownconverted together simultaneously from radio frequency spectrum. Inexemplary embodiments, the uplink radio system signal is not specific toa particular channel and does not require any baseband processing whenconverted from radio frequency, while uplink channelized data isspecific to a particular channel and requires baseband processing whenbeing converted from radio frequency.

In exemplary embodiments, an optional network interface clock unit iscommunicatively coupled to an external device clock unit of the CPRIbase station 108D and a master reference clock is provided as describedabove with reference to FIG. 2A.

FIG. 3 is a block diagram of an exemplary embodiment of an antenna unit104 used in distributed antenna systems, such as the exemplarydistributed antenna system 100 described above. The antenna unit 104includes a signal multiplexing module 302, at least one radio frequency(RF) conversion module 304 (including RF conversion module 304-1 and anyamount of optional RF conversion modules 304 through optional RFconversion module 304-C), network interface module 306, optionalEthernet interface 308, optional downlink network interface module 310,optional antenna unit clock unit 312, optional processor 314, optionalmemory 316, and optional power supply 318. In exemplary embodiments,signal multiplexing module 302, at least one RF conversion module 304,and/or the network interface module 306 are implemented at least in partby optional processor 314 and optional memory 316. In exemplaryembodiments, optional power supply 318 is used to power the variouscomponents of the antenna unit 104.

In exemplary embodiments, signal multiplexing module 302 receives atleast one downlink radio system signal from at least one signalinterface unit 102 through the distributed switching network 106. Inexemplary embodiments, the at least one downlink radio system signal isreceived through the network interface module 306. In exemplaryembodiments where the downlink radio system signal is an optical signal,the network interface module 306 converts the downlink radio systemsignal from an optical format to an electrical format. In exemplaryembodiments, more input lines and/or more network interface module 306are included in the antenna unit 104. In exemplary embodiments, thesignal multiplexing module 302 splits apart an aggregate downlink radiosystem signal into at least one downlink radio system signal that issent to RF conversion module 304-1 for eventual transmission as a radiofrequency on radio frequency antenna 116-1. In exemplary embodiments,the signal multiplexing module 302 splits apart the aggregate downlinkradio system signal into a plurality of downlink radio system signalsthat are sent to a plurality of RF conversion modules 304 for eventualtransmission as radio frequency signals at radio frequency antennas 116.

In exemplary embodiments, signal multiplexing module 302 receives atleast one uplink radio system signal from at least one RF conversionmodule 304. In exemplary embodiments, the signal multiplexing module 302receives a plurality of uplink radio system signals from a plurality ofRF conversion modules 304. In exemplary embodiments, the radio systemsignal multiplexing unit aggregates at least one uplink radio systemsignal received from an RF conversion module 304-1 with another uplinkradio system signal received from another RF conversion module 304. Inexemplary embodiments, the signal multiplexing module 302 aggregates aplurality of uplink radio system signals into a single aggregate uplinkradio system signal. In exemplary embodiments, the aggregate uplinkradio system signal is provided to network interface module 306 whichconverts the aggregate uplink radio system signal from electricalsignals to optical signals before communicating the aggregate uplinkradio system signal to the distributed switching network 106. In otherembodiments, the aggregate uplink radio system signal is communicated aselectrical signals to the distributed switching network 106. Inexemplary embodiments, the aggregate uplink signal is converted tooptical signals at another place in the distributed antenna system 100.

In exemplary embodiments, the optional Ethernet interface 308 receives adownlink radio system signal from the signal multiplexing module 302 andconverts it to Ethernet packets and communicates the Ethernet packetswith an internet protocol network device. The optional Ethernetinterface 308 also receives Ethernet packets from the internet protocolnetwork device and converts them to an uplink radio system signal andcommunicates it to the signal multiplexing module 302. In exemplaryembodiments having the optional Ethernet interface 308, a correspondingexternal device 108 that is an Ethernet interface interfaces with asignal interface unit 102 that is an Ethernet interface.

In exemplary embodiments, the optional downlink network interface module310 receives a downlink radio system signal from the signal multiplexingmodule 302 and communicates it with a downlink device across a downlinkcommunication medium. In exemplary embodiments, the downlink device isanother antenna unit 104.

In exemplary embodiments, the optional antenna unit clock unit 312extracts the master reference clock from the downlink radio systemsignal and uses this master clock within the antenna unit 104 toestablish a common time base in the antenna unit 104 with the rest ofthe distributed antenna system 100. In exemplary embodiments, theoptional antenna unit clock unit 312 generates a master reference clockand distributes the generated master reference clock to other componentsof the distributed antenna system 100 (and even the external devices108) in the upstream using the uplink radio system signal.

FIGS. 4A-4C are block diagrams of exemplary embodiments of RF conversionmodules 304 used in antenna units of distributed antenna systems, suchas the exemplary antenna unit 104 described above. Each of FIGS. 4A-4Care block diagrams of exemplary embodiments of RF conversion module 304,labeled RF conversion module 304A-304C respectively.

FIG. 4A is a block diagram of an exemplary RF conversion module 304Aincluding an optional radio system signal conditioner 402, an RFfrequency converter 404, an optional RF conditioner 406, and an RFduplexer 408 coupled to a single radio frequency antenna 116.

The optional radio system signal conditioner 402 is communicativelycoupled to a signal multiplexing module 302 and the radio frequency (RF)frequency converter 404. In the forward path, the optional radio systemsignal conditioner 402 conditions the downlink radio system signal (forexample, through amplification, attenuation, and filtering) receivedfrom the signal multiplexing module 302 and passes the downlink radiosystem signal to the RF frequency converter 404. In the reverse path,the optional radio system signal conditioner 402 conditions the uplinkradio system signal (for example, through amplification, attenuation,and filtering) received from the RF frequency converter 404 and passesthe uplink radio system signal to the signal multiplexing module 302.

The RF frequency converter 404 is communicatively coupled to either thesignal multiplexing module 302 or the optional radio system signalconditioner 402 on one side and to either RF duplexer 408 or theoptional RF conditioner 406 on the other side. In the downstream, the RFfrequency converter 404 converts a downlink radio system signal todownlink radio frequency (RF) signals and passes the downlink RF signalsonto either the RF duplexer 408 or the optional RF conditioner 406. Inthe upstream, the RF frequency converter 404 converts uplink radiofrequency (RF) signals received from either the RF duplexer 408 or theoptional RF conditioner 406 to an uplink radio system signal and passesthe uplink radio system signal to either the signal multiplexing module302 or the optional radio system signal conditioner 402.

The RF duplexer 408 is communicatively coupled to either the RFfrequency converter 404 or the optional RF conditioner 406 on one sideand the radio frequency antenna 116 on the other side. The RF duplexer408 duplexes the downlink RF signals with the uplink RF signals fortransmission/reception using the radio frequency antenna 116. Inexemplary embodiments, the downlink and uplink signals within a radiofrequency band are distinct in spectrum and are separated in a frequencyusing a Frequency Division Duplexing (FDD) scheme. In other embodiments,either or both of the downlink and uplink signals within the radiofrequency band are separated in time using a Time Division Duplexing(TDD) scheme. In exemplary embodiments, downlink and uplink signalswithin a radio frequency band overlap in spectrum and are separated intime using a Time Division Duplexing (TDD) scheme.

FIG. 4B is a block diagram of an exemplary RF conversion module 304Bincluding an optional radio system signal conditioner 402, an RFfrequency converter 404, and an optional RF conditioner 406 coupled to adownlink radio frequency antenna 116A and an uplink radio frequencyantenna 116B. RF conversion module 304B includes similar components toRF conversion module 304A and operates according to similar principlesand methods as RF conversion module 304A described above. The differencebetween RF conversion module 304B and RF conversion module 304A is thatRF conversion module 304B does not include RF duplexer 408 and insteadincludes separate downlink radio frequency antenna 116A used to transmitRF signals to at least one subscriber unit and uplink radio frequencyantenna 116B used to receive RF signals from at least one subscriberunit.

FIG. 4C is a block diagram of an exemplary RF conversion module 304C-1and exemplary RF conversion module 304C-2 that share a single radiofrequency antenna 116 through an RF diplexer 410. The RF conversionmodule 304C-1 includes an optional radio system signal conditioner402-1, an RF frequency converter 404-1, an optional RF conditioner406-1, and an RF duplexer 408-1 communicatively coupled to RF diplexer410 that is communicatively coupled to radio frequency antenna 116.Similarly, the RF conversion module 304C-2 includes an optional radiosystem signal conditioner 402-2, an RF frequency converter 404-2, anoptional RF conditioner 406-2, and an RF duplexer 408-2 communicativelycoupled to RF diplexer 410 that is communicatively coupled to radiofrequency antenna 116. Each of RF conversion module 304C-1 and 304C-2operate according to similar principles and methods as RF conversionmodule 304A described above. The difference between RF conversionmodules 304C-1 and 304C-2 and RF conversion module 304A is that RFconversion modules 304C-1 and 304C-2 are both coupled to a single radiofrequency antenna 116 through RF diplexer 410. The RF diplexer 410diplexes the duplexed downlink and uplink signals for both RF conversionmodule 304C-1 and 304C-2 for transmission/reception using the singleradio frequency antenna 116.

FIGS. 5A-5B are block diagrams of an exemplary embodiment of an antennaunit 104 used in distributed antenna systems, such as the exemplarydistributed antenna system 100 described above. Each of FIGS. 5A-5B areblock diagrams of exemplary embodiments of antenna unit 104, labeledantenna unit 104A-104B respectively.

FIG. 5A is a block diagram of an exemplary embodiment of an antenna unit104A used without a distributed antenna system. Antenna unit 104Aincludes similar components to the antenna unit 104 including a signalmultiplexing module 302, at least one radio frequency (RF) conversionmodule 304 (including RF conversion module 304-1 and any amount ofoptional RF conversion modules 304 through optional RF conversion module304-C), a plurality of network interface modules 306 (including networkinterface module 306-1, network interface module 306-2, and any amountof optional network interface module 306 through optional networkinterface module 306-A), optional Ethernet interface 308, optionaldownlink network interface module 310, optional antenna unit clock unit312, optional processor 314, optional memory 316, and optional powersupply 318. In exemplary embodiments, signal multiplexing module 302, atleast one RF conversion module 304, and/or the network interface module306 are implemented at least in part by optional processor 314 andoptional memory 316. In exemplary embodiments, optional power supply 318is used to power the various components of the antenna unit 104A.

Antenna unit 104A includes similar components to antenna unit 104 andoperates according to similar principles and methods as antenna unit 104described above. The difference between antenna unit 104A and antennaunit 104 is that antenna unit 104A includes a plurality of networkinterface modules 306 communicatively coupled to a plurality of signalinterface units 102 that are each coupled either directly to an externaldevice 108 or through an optional backhaul network 110. In exemplaryembodiments, the backhaul network 110 is a baseband base station networktransporting I/Q samples from a baseband base station acting as theexternal device 108. In exemplary embodiments, the backhaul network 110is a CPRI base station network transporting CPRI signals from a CPRIbase station acting as the external device 108. In exemplaryembodiments, the backhaul network 110 is a SONET network transportingSONET frames from a SONET network interface acting as the externaldevice 108. In exemplary embodiments, the backhaul network 110 is anEthernet network, transporting Ethernet frames and/or Internet Protocol(IP) packets from an Ethernet network interface acting as the externaldevice 108. In exemplary embodiments, various signal interface units 102interface with various types of external devices 108 and couple with thesingle antenna unit 104B. Accordingly, the antenna unit 104A itself caninterface with asynchronous external devices 108 and each signalinterface unit 102 converts the clock from the various clocks of theexternal devices 108 to a common clock of the antenna unit 104B. Thesignal interface units 102 further convert the various types of signalsof the external devices into the radio system signal used by the antennaunit 104A and are interfaced with the various network interface modules306. In exemplary embodiments, the signal multiplexing module canmultiplex radio system signals derived from the various external devices108 into at least one signal communicated to one or more RF conversionmodules 304.

FIG. 5B is a block diagram of an exemplary embodiment of an antenna unit104B used without a distributed antenna system. Antenna unit 104Bincludes similar components to the antenna unit 104B including signalmultiplexing module 302, at least one radio frequency (RF) conversionmodule 304 (including RF conversion module 304-1 and any amount ofoptional RF conversion modules 304 through optional RF conversion module304-C), optional Ethernet interface 308, optional downlink networkinterface module 310, optional antenna unit clock unit 312, optionalprocessor 314, optional memory 316, and optional power supply 318. Inexemplary embodiments, signal multiplexing module 302, at least one RFconversion module 304, and/or the network interface module 306 areimplemented at least in part by optional processor 314 and optionalmemory 316. In exemplary embodiments, optional power supply 318 is usedto power the various components of the antenna unit 104A.

Antenna unit 104B includes similar components to antenna unit 104A andoperates according to similar principles and methods as antenna unit 104and antenna unit 104B described above. The difference between antennaunit 104B and antenna unit 104A is that instead of the plurality ofnetwork interface modules 306, antenna unit 104B includes a plurality ofsignal interface units 102 (including signal interface unit 102-1,signal interface unit 102-2, and any amount of optional signal interfaceunits 102 through optional signal interface unit 102-A) communicativelycoupled either directly to an external device 108 or through an optionalbackhaul network 110. Essentially, antenna unit 104B brings the signalinterface unit 102 functionality into the antenna unit 104B instead ofhaving them as stand alone units. Other than that change, it operates asdescribed above.

In other embodiments, an antenna unit 104 may have a combination ofintegrated signal interface units 102, external signal interface units102, and coupling with a distributed switching network as various inputsto the antenna unit 104 based on the various embodiments shown in FIG. 3and FIGS. 5A-5B.

FIG. 6 is a flow diagram illustrating one exemplary embodiment of amethod 600 for re-clocking a downlink channelized radio carrier at asignal interface unit. Exemplary method 600 begins at block 602 withreceiving a downlink channelized radio carrier signal for a radiofrequency carrier at a signal interface unit from a channelized radiocarrier base station interface. Exemplary method 600 proceeds to block604 with re-clocking the downlink channelized radio carrier signal to amaster clock of the radio system from a clock of the channelized radiocarrier base station interface at the signal interface unit. Exemplarymethod 600 proceeds to block 606 with communicating at least one of there-clocked downlink channelized radio carrier signal and a downlinkdigitized radio frequency signal based on the re-clocked downlinkchannelized radio carrier signal from the signal interface unit to theantenna unit.

FIG. 7 is a flow diagram illustrating one exemplary embodiment of amethod 700 for re-clocking an uplink channelized radio carrier at asignal interface unit. Exemplary method 700 begins at block 702 withreceiving at least one of an uplink digitized radio frequency signal andan uplink channelized radio carrier signal from an antenna unit at asignal interface. Exemplary method 700 proceeds to block 704 withre-clocking the uplink channelized radio carrier signal to a clock of anexternal device from a master clock of the radio system at the signalinterface. Exemplary method 700 proceeds to block 706 with communicatingthe uplink channelized radio carrier signal for a radio frequencycarrier to the external device from the signal interface unit.

FIG. 8 is a flow diagram illustrating one exemplary embodiment of amethod 800 for interfacing a plurality of asynchronous downlink radiocarrier signals in a distributed antenna system. Exemplary method 800begins at block 802 with receiving a plurality of asynchronous downlinkradio carrier signals for a plurality of radio frequency carriers fromat least one channelized radio carrier base station interface at aplurality of network interface units, each of the plurality ofasynchronous downlink radio carrier signals having a different clock.Exemplary method 800 proceeds to block 804 with re-clocking theplurality of downlink asynchronous radio carrier signals to a masterclock of the distributed antenna system from each different clock ofeach of the plurality of asynchronous downlink radio carrier signals ata plurality of network interface units. Exemplary method 800 proceeds toblock 806 with converting the plurality of downlink asynchronous radiocarrier signal to downlink digitized radio frequency signals at theplurality of network interface units. Exemplary method 800 proceeds toblock 808 with communicating the downlink digitized radio frequencysignals from the plurality of signal interface units to the host unit.Exemplary method 800 proceeds to block 810 with combining at least twoof the plurality of downlink digitized radio frequency signals into anaggregate downlink digitized radio frequency signal at a host unit.Exemplary method 800 proceeds to block 812 with communicating theaggregate downlink digitized radio frequency signal from the host unitto the antenna unit. Exemplary method 800 proceeds to block 814 withconverting at least one of the aggregate downlink digitized radiofrequency signal and another signal based on the aggregate downlinkdigitized radio frequency signal into downlink radio frequency signalsat the antenna unit. Exemplary method 800 proceeds to optional block 816with wirelessly transmitting the downlink radio frequency signals to atleast one subscriber unit.

FIG. 9 is a flow diagram illustrating one exemplary embodiment of amethod 900 for interfacing a plurality of asynchronous uplink radiocarrier signals in a distributed antenna system. Exemplary method 900begins at optional block 902 with receiving uplink radio frequencysignals from at least one subscriber unit. Exemplary method 900 proceedsto block 904 with converting the uplink radio frequency signals into anaggregate uplink digitized radio frequency signal. Exemplary method 900proceeds to block 906 with communicating the aggregate uplink digitizedradio frequency signal from the antenna unit to the host unit. Exemplarymethod 900 proceeds to block 908 with extracting a plurality of uplinkdigitized radio frequency signals from the aggregate uplink digitizedradio frequency signal at the host unit. Exemplary method 900 proceedsto block 910 with communicating the plurality of uplink digitized radiofrequency signals from the host unit to a plurality of signal interfaceunits. Exemplary method 900 proceeds to block 912 with converting theplurality of uplink digitized radio frequency signals into a pluralityof uplink channelized radio carrier signals at a plurality of networkinterface units. Exemplary method 900 proceeds to block 914 withre-clocking the plurality of uplink radio carrier signals from themaster clock of the distributed antenna system to each different clockof each of the plurality of asynchronous uplink radio carrier signals atthe plurality of network interface units. Exemplary method 900 proceedsto block 916 with communicating the plurality of asynchronous uplinkradio carriers signals for the plurality of radio frequency carriersfrom the plurality of network interface units to at least onechannelized radio carrier base station interface, each of the pluralityof asynchronous uplink radio carrier signals having a different clock.

FIG. 10 is a flow diagram illustrating one exemplary embodiment of amethod 1000 for interfacing a plurality of asynchronous downlink radiocarrier signals at an antenna unit. Exemplary method 1000 begins atblock 1002 with receiving a plurality of asynchronous downlink radiocarrier signals for a plurality of radio frequency carriers form atleast one radio carrier base station interface at an antenna unit, eachof the plurality of asynchronous downlink radio carrier signals having adifferent clock. Exemplary method 1000 proceeds to block 1004 withre-clocking the plurality of downlink asynchronous radio carriers signalto a master clock of an antenna unit from each different clock of eachof the plurality of asynchronous downlink radio carrier signals at theantenna unit. Exemplary method 1000 proceeds to block 1006 withconverting the plurality of downlink asynchronous radio carrier signalsto downlink analog intermediate frequency signals at the antenna unit.Exemplary method 1000 proceeds to block 1008 with combining at least twoof the plurality of downlink analog intermediate frequency signals intoan aggregate downlink analog intermediate frequency signal at theantenna unit. Exemplary method 1000 proceeds to block 1010 withconverting the aggregate downlink analog intermediate frequency signalinto downlink radio frequency signals at the antenna unit. Exemplarymethod 1000 proceeds to optional block 1012 with wirelessly transmittingdownlink radio frequency signals to at least one subscriber unit fromthe antenna unit.

FIG. 11 is a flow diagram illustrating one exemplary embodiment of amethod 1100 for interfacing a plurality of asynchronous uplink radiocarrier signals at an antenna unit. Exemplary method 1100 begins atoptional block 1102 with receiving uplink radio frequency signals fromat least one subscriber unit. Exemplary method 1100 proceeds to block1104 with converting uplink radio frequency signals into an aggregateuplink analog intermediate frequency signal at antenna unit. Exemplarymethod 1100 proceeds to block 1106 with splitting apart the aggregateuplink analog intermediate frequency signal into a plurality of uplinkanalog intermediate frequency signals at the antenna unit. Exemplarymethod 1100 proceeds to block 1108 with converting the plurality ofuplink analog intermediate frequency signals to a plurality of uplinkradio carrier signals at the antenna unit. Exemplary method 1100proceeds to block 1110 with re-clocking the plurality of uplink radiocarrier signals from a master clock of the antenna unit to eachdifferent clock of the plurality of asynchronous uplink radio carriersignals at the antenna unit. Exemplary method 1100 proceeds to block1112 with communicating the plurality of asynchronous uplink radiocarrier signals for the plurality of radio frequency carriers from theantenna unit to at least one radio carrier base station interface, eachof the plurality of asynchronous uplink radio carrier signals having adifferent clock.

Any of the processors described above may include or function withsoftware programs, firmware or other computer readable instructions forcarrying out various methods, process tasks, calculations, and controlfunctions, described herein. These instructions are typically stored onany appropriate computer readable medium used for storage of computerreadable instructions or data structures. The computer readable mediumcan be implemented as any available media that can be accessed by ageneral purpose or special purpose computer or processor, or anyprogrammable logic device. Suitable processor-readable media may includestorage or memory media such as magnetic or optical media. For example,storage or memory media may include conventional hard disks, CompactDisk-Read Only Memory (CD-ROM), volatile or non-volatile media such asRandom Access Memory (RAM) (including, but not limited to, SynchronousDynamic Random Access Memory (SDRAM), Double Data Rate (DDR) RAM, RAMBUSDynamic RAM (RDRAM), Static RAM (SRAM), etc.), Read Only Memory (ROM),Electrically Erasable Programmable ROM (EEPROM), and flash memory, etc.Suitable processor-readable media may also include transmission mediasuch as electrical, electromagnetic, or digital signals, conveyed via acommunication medium such as a network and/or a wireless link.

Although specific embodiments have been illustrated and describedherein, it will be appreciated by those of ordinary skill in the artthat any arrangement, which is calculated to achieve the same purpose,may be substituted for the specific embodiments shown. Therefore, it ismanifestly intended that this invention be limited only by the claimsand the equivalents thereof.

EXAMPLE EMBODIMENTS

Example 1 includes a signal interface unit in a radio system,comprising: an external device interface configured to receive adownlink asynchronous radio carrier signal for a radio frequency carrierfrom an external device; a clock conversion unit communicatively coupledto the external device interface and configured to re-clock the downlinkasynchronous radio carrier signal to a master clock of the radio systemfrom the clock of the external device; and an antenna side interfaceconfigured to communicate at least one of the re-clocked downlinkasynchronous radio carrier signal and a downlink digitized radiofrequency signal based on the re-clocked downlink asynchronous radiocarrier signal to an antenna unit.

Example 2 includes the signal interface unit of Example 1, wherein theclock conversion unit includes a resampling filter that re-clocks thedownlink asynchronous radio carrier signal to the master clock of theradio system from the clock of the external device.

Example 3 includes the signal interface unit of any of Examples 1-2,wherein the clock conversion unit converts from a first clock domain ofthe external device to a second clock domain of the radio system using aFarrow structure.

Example 4 includes the signal interface unit of any of Examples 1-3,wherein the clock conversion unit is configured to re-clock the downlinkasynchronous radio carrier signal by converting first samples of achannelized radio carrier synchronous with a first clock of a firstclock domain to second samples synchronous with a second clock of asecond clock domain.

Example 5 includes the signal interface unit of any of Examples 1-4,wherein the downlink asynchronous radio carrier signal is specific to aparticular channel and requires additional baseband conversion beforeradio frequency conversion and transmission can be performed; andwherein the downlink digitized radio frequency signal is not specific toa particular channel and does not require additional baseband conversionbefore radio frequency conversion and transmission can be performed.

Example 6 includes the signal interface unit of any of Examples 1-5,wherein the downlink asynchronous radio carrier signal includes I/Qpairs.

Example 7 includes the signal interface unit of any of Examples 1-6,further comprising: a signal conversion module communicatively coupledbetween the external device interface and the antenna side interface andconfigured to generate the downlink digitized radio frequency signalbased on the re-clocked downlink asynchronous radio carrier signal.

Example 8 includes the signal interface unit of any of Examples 1-7,wherein the antenna unit is a remote antenna unit communicativelycoupled to the signal interface unit by at least one medium.

Example 9 includes the signal interface unit of Example 8, wherein thedistributed antenna system network interface is configured tocommunicate the downlink digital radio frequency signal directly to theremote antenna unit across the at least one medium.

Example 10 includes the signal interface unit of any of Examples 8-9,wherein the signal interface is communicatively coupled with anintermediary device that aggregates the downlink digital radio frequencysignal with at least one other downlink digital radio frequency signalbefore being transmitted to the remote antenna unit.

Example 11 includes the signal interface unit of Example 10, whereinindividual channels within the downlink digital radio frequency signaland the at least one other downlink digital radio frequency signal donot overlap and can be upconverted together simultaneously to radiofrequency spectrum.

Example 12 includes the signal interface unit of any of Examples 8-11,wherein the at least one medium includes at least one of a wired mediumand a wireless medium.

Example 13 includes the signal interface unit of any of Examples 8-12,wherein the signal interface communicates at least one of digitalsignals and analog signals to the remote antenna unit across the atleast one medium.

Example 14 includes the signal interface unit of any of Examples 1-13,wherein the external device is part of a base band unit of a basestation.

Example 15 includes the signal interface unit of any of Examples 1-14,wherein the external device is at least one of a Common Public RadioInterface (CPRI) base station interface, an Open Base StationArchitecture Initiative (OBSAI) base station interface, and an OpenRadio Interface (ORI) interface; and wherein the downlink asynchronousradio carrier signal is formatted according to at least one of a CommonPublic Radio Interface (CPRI) standard, an Open Base StationArchitecture Initiative (OBSAI) standard, and an Open Radio Interface(ORI) standard.

Example 16 includes the signal interface unit of any of Examples 1-15,wherein the downlink digital radio frequency signal contains a digitalrepresentation of the radio carrier positioned within a set of spectrumthat reflects its eventual location within radio frequency spectrum.

Example 17 includes the signal interface unit of any of Examples 1-16,further comprising: wherein the antenna side interface is configured toreceive at least one of an uplink digitized radio frequency signal andan uplink channelized radio carrier signal from the antenna unit;wherein the clock conversion unit is further configured to re-clock theuplink channelized radio carrier signal to the clock of the externaldevice from the master clock of the radio system; and wherein theexternal device interface is further configured to communicate an uplinkchannelized radio carrier signal for the radio frequency carrier to theexternal device.

Example 18 includes a method comprising: receiving a downlinkasynchronous radio carrier signal for a radio frequency carrier at asignal interface unit from an external device; re-clocking the downlinkasynchronous radio carrier signal to a master clock of the radio systemfrom the clock of the external device at the signal interface unit; andcommunicating at least one of the re-clocked downlink asynchronous radiocarrier signal and a downlink digitized radio frequency signal based onthe re-clocked downlink asynchronous radio carrier signal from thesignal interface unit to an antenna unit.

Example 19 includes the method of Example 18, wherein re-clocking thedownlink asynchronous radio carrier signal to a master clock of theradio system from the clock of the external device at the signalinterface unit occurs at least in part through a resampling filter.

Example 20 includes the method of any of Examples 18-19, whereinre-clocking the downlink asynchronous radio carrier signal to a masterclock of the radio system from the clock of the external device at thesignal interface unit includes converting from a first clock domain ofthe external device to a second clock domain of the radio system using aFarrow structure.

Example 21 includes the method of any of Examples 18-20, whereinre-clocking the downlink asynchronous radio carrier signal to a masterclock of the radio system from the clock of the external device at thesignal interface unit includes converting first samples of a channelizedradio carrier synchronous with a first clock of a first clock domain tosecond samples synchronous with a second clock of a second clock domain.

Example 22 includes the method of any of Examples 18-21, wherein thedownlink asynchronous radio carrier signal is specific to a particularchannel and requires additional baseband conversion before radiofrequency conversion and transmission can be performed; and wherein thedownlink digitized radio frequency signal is not specific to aparticular channel and does not require additional baseband conversionbefore radio frequency conversion and transmission can be performed.

Example 23 includes the method of any of Examples 18-22, wherein thedownlink asynchronous radio carrier signal includes I/Q pairs.

Example 24 includes the method of any of Examples 18-23, furthercomprising: generating the downlink digitized radio frequency signalbased on the re-clocked downlink asynchronous radio carrier signal.

Example 25 includes the method of any of Examples 18-24, wherein theantenna unit is a remote antenna unit communicatively coupled to thesignal interface unit by at least one medium.

Example 26 includes the method of Example 25, wherein communicating theat least one of the re-clocked downlink asynchronous radio carriersignal and a downlink digitized radio frequency signal based on there-clocked downlink asynchronous radio carrier signal from the signalinterface unit to an antenna unit occurs across the at least one medium.

Example 27 includes the method of any of Examples 25-26, furthercomprising aggregating the downlink digital radio frequency signal withat least one other downlink digital radio frequency signal at anintermediary device communicatively coupled between the signal interfaceand the remote antenna unit before being transmitted to the remoteantenna unit.

Example 28 includes the method of Example 27, wherein individualchannels within the downlink digital radio frequency signal and the atleast one other downlink digital radio frequency signal do not overlapand can be upconverted together simultaneously to radio frequencyspectrum.

Example 29 includes the method of any of Examples 18-28, wherein theexternal device is part of a base band unit of a base station.

Example 30 includes the method of any of Examples 18-29, wherein theexternal device is at least one of a Common Public Radio Interface(CPRI) base station interface, an Open Base Station ArchitectureInitiative (OBSAI) base station interface, and an Open Radio Interface(ORI) interface; and wherein the downlink asynchronous radio carriersignal is formatted according to at least one of a Common Public RadioInterface (CPRI) standard, an Open Base Station Architecture Initiative(OBSAI) standard, and an Open Radio Interface (ORI) standard.

Example 31 includes the method of any of Examples 18-30, wherein thedownlink digital radio frequency signal contains a digitalrepresentation of the radio carrier positioned within a set of spectrumthat reflects its eventual location within radio frequency spectrum.

Example 32 includes the method of any of Examples 18-31, furthercomprising: receiving at least one of an uplink digitized radiofrequency signal and an uplink channelized radio carrier signal from theantenna unit at the signal interface; re-clocking the uplink channelizedradio carrier signal to the clock of the external device from the masterclock of the radio system at the signal interface; and communicating anuplink channelized radio carrier signal for the radio frequency carrierto the external device from the signal interface unit.

Example 33 includes a distributed antenna system, comprising: aplurality of signal interface units configured to receive a plurality ofdownlink asynchronous radio carrier signals for a plurality of radiofrequency carriers from at least one external device, each of theplurality of downlink asynchronous radio carrier signals having adifferent clock; wherein the plurality of signal interface units isfurther configured to re-clock the plurality of downlink asynchronousradio carrier signals to a master clock of the distributed antennasystem from each different clock of each of the plurality of downlinkasynchronous radio carrier signal; wherein the plurality of signalinterface units is further configured to convert the plurality ofdownlink asynchronous radio carrier signals to downlink digitized radiofrequency signals; a host unit communicatively coupled to the pluralityof signal interface units and configured to combine at least two of theplurality of downlink digitized radio frequency signals into anaggregate downlink digitized radio frequency signal; an antenna unitcommunicatively coupled to the host unit and configured to receive theaggregate downlink digitized radio frequency signal from the host unit;wherein the antenna unit is further configured to convert at least oneof the aggregate downlink digitized radio frequency signal and anothersignal based on the aggregate downlink digitized radio frequency signalinto downlink radio frequency signals; wherein the antenna unit isfurther configured to wirelessly transmit the downlink radio frequencysignals to at least one subscriber unit.

Example 34 includes the distributed antenna system of Example 33,wherein the plurality of signal interface units includes at least oneresampling filter that re-clocks the plurality of downlink asynchronousradio carrier signals to the master clock of the remote antenna unitfrom each different clock of each of the plurality of downlinkasynchronous radio carrier signal.

Example 35 includes the distributed antenna system of any of Examples33-34, wherein the plurality of signal interface units is configured toconvert from first clock domains of the external devices to a secondclock domain of the remote antenna unit using a Farrow structure.

Example 36 includes the distributed antenna system of any of Examples33-35, wherein at least one of the plurality of signal interface unitsis configured to re-clock at least one downlink asynchronous radiocarrier signal by converting first samples of a channelized radiocarrier synchronous with a first clock of a first clock domain to secondsamples synchronous with a second clock of a second clock domain.

Example 37 includes the distributed antenna system of any of Examples33-36, wherein at least one of the plurality of downlink asynchronousradio carrier signals is specific to a particular channel and requiresadditional baseband conversion before radio frequency conversion andtransmission can be performed; and wherein the aggregate downlink analogintermediate frequency signal is not specific to a particular channeland does not require additional baseband conversion before radiofrequency conversion and transmission can be performed.

Example 38 includes the distributed antenna system of any of Examples33-37, wherein at least one of the downlink asynchronous radio carriersignals includes I/Q pairs.

Example 39 includes the distributed antenna system of any of Examples33-38, wherein individual channels within the at least two of theplurality of downlink analog intermediate frequency signals do notoverlap and can be upconverted together simultaneously to radiofrequency spectrum once combined into the aggregate downlink analogintermediate frequency signal.

Example 40 includes the distributed antenna system of any of Examples33-39, wherein at least one of the plurality of external devices is abaseband processing unit of a base station.

Example 41 includes the distributed antenna system of any of Examples33-40, wherein at least one of the plurality of downlink asynchronousradio carrier signals received at the plurality of signal interfaceunits uses at least one of a SONET protocol and an Ethernet protocol toreceive I/Q pairs.

Example 42 includes the distributed antenna system of any of Examples33-41, wherein at least one of the plurality of network interfaces is atleast one of a Common Public Radio Interface (CPRI) base stationinterface, an Open Base Station Architecture Initiative (OBSAI) basestation interface, and an Open Radio Interface (ORI) interface; andwherein at least one of the downlink asynchronous radio carrier signalis formatted according to at least one of a Common Public RadioInterface (CPRI) standard, an Open Base Station Architecture Initiative(OBSAI) standard, and an Open Radio Interface (ORI) standard.

Example 43 includes the distributed antenna system of any of Examples33-42, wherein at least one of the downlink asynchronous radio carriersignal contains a digital representation of a radio carrier positionedwithin a set of spectrum that reflects its eventual location withinradio frequency spectrum.

Example 44 includes the distributed antenna system of any of Examples33-43, further comprising: wherein the plurality of signal interfaceunits is further configured to convert a plurality of uplink digitizedradio frequency signals to uplink asynchronous radio carrier signals atleast in part by re-clocking a plurality of the uplink digitized radiofrequency signals to a plurality of asynchronous clocks, different fromthe master clock of the distributed antenna system.

Example 45 includes a method for interfacing a plurality of asynchronousdownlink asynchronous radio carrier signal in a distributed antennasystem, comprising: receiving a plurality of downlink asynchronous radiocarrier signals for a plurality of radio frequency carriers at aplurality of signal interface units from at least one external device,each of the plurality of downlink asynchronous radio carrier signalshaving a different clock; re-clocking the plurality of downlinkasynchronous radio carrier signals to a master clock of the distributedantenna system from each different clock of each of the plurality ofdownlink asynchronous radio carrier signals at the plurality of signalinterface units; converting the plurality of downlink asynchronous radiocarrier signals to downlink digitized radio frequency signals at theplurality of signal interface units; communicating the downlinkdigitized radio frequency signals from the plurality of signal interfaceunits to a host unit; combining at least two of the plurality ofdownlink digitized radio frequency signals into an aggregate downlinkdigitized radio frequency signal at the host unit; communicating theaggregate downlink digitized radio frequency signal from the host unitto an antenna unit; and converting at least one of the aggregatedownlink digitized radio frequency signal and another signal based onthe aggregate downlink digitized radio frequency signal into downlinkradio frequency signals at the antenna unit.

Example 46 includes the method of Example 45, further comprising:wirelessly transmitting the downlink radio frequency signals to at leastone subscriber unit.

Example 47 includes the method of any of Examples 45-46, whereinre-clocking the plurality of downlink asynchronous radio carrier signalsto the master clock of the antenna unit from each different clock ofeach of the plurality of downlink asynchronous radio carrier signals atthe antenna unit occurs through at least one resampling filter.

Example 48 includes the method of any of Examples 45-47, whereinre-clocking the plurality of downlink asynchronous radio carrier signalsto the master clock of the antenna unit converts the plurality ofdownlink asynchronous radio carrier signals from first clock domains ofthe plurality of channelized radio carrier signals to a second clockdomain of the antenna unit using a Farrow structure.

Example 49 includes the method of any of Examples 45-48, whereinre-clocking the plurality of downlink asynchronous radio carrier signalsto the master clock of the antenna unit includes converting firstsamples of a channelized radio carrier synchronous with a first clock ofa first clock domain to second samples synchronous with a second clockof a second clock domain.

Example 50 includes the method of any of Examples 45-49, wherein each ofthe plurality of downlink asynchronous radio carrier signals is specificto a particular channel and requires additional baseband conversionbefore radio frequency conversion and transmission can be performed; andwherein the aggregate downlink analog intermediate frequency signal isnot specific to a particular channel and does not require additionalbaseband conversion before radio frequency conversion and transmissioncan be performed.

Example 51 includes the method of any of Examples 45-50, wherein each ofthe downlink asynchronous radio carrier signal includes I/Q pairs.

Example 52 includes the method of any of Examples 45-51, whereinindividual channels within the at least two of the plurality of downlinkanalog intermediate frequency signals do not overlap and can beupconverted together simultaneously to radio frequency spectrum oncecombined into the aggregate downlink analog intermediate frequencysignal.

Example 53 includes the method of any of Examples 45-52, wherein atleast one of the plurality of external devices is at least one of abaseband processing unit of a base station.

Example 54 includes the method of any of Examples 45-53, whereinreceiving at least one of the plurality of downlink asynchronous radiocarrier signals for the plurality of radio frequency carriers occursusing at least one of a SONET protocol and an Ethernet protocol totransmit I/Q pairs.

Example 55 includes the method of any of Examples 45-54, wherein atleast one of the plurality of network interfaces is at least one of aCommon Public Radio Interface (CPRI) base station interface, an OpenBase Station Architecture Initiative (OBSAI) base station interface, andan Open Radio Interface (ORI) interface; and wherein at least one of thedownlink asynchronous radio carrier signal is formatted according to atleast one of a Common Public Radio Interface (CPRI) standard, an OpenBase Station Architecture Initiative (OBSAI) standard, and an Open RadioInterface (ORI) standard.

Example 56 includes the method of any of Examples 45-55, wherein atleast one of the downlink asynchronous radio carrier signal contains adigital representation of a radio carrier positioned within a set ofspectrum that reflects its eventual location within radio frequencyspectrum.

Example 57 includes the method of any of Examples 45-56, furthercomprising: converting a plurality of uplink digitized radio frequencysignals to uplink asynchronous radio carrier signals at the plurality ofsignal interface units at least in part by re-clocking a plurality ofthe uplink digitized radio frequency signals to a plurality ofasynchronous clocks, different from the master clock of the distributedantenna system.

Example 58 includes a remote antenna unit, comprising: a plurality ofnetwork interfaces configured to receive a plurality of downlinkasynchronous radio carrier signals for a plurality of radio frequencycarriers from at least one external device, each of the plurality ofdownlink asynchronous radio carrier signals having a different clock; atleast one clock conversion unit communicatively coupled to the pluralityof external device interfaces and configured to re-clock the pluralityof downlink asynchronous radio carrier signals to a master clock of theremote antenna unit from each different clock of each of the pluralityof downlink asynchronous radio carrier signal; at least one intermediatefrequency convertor communicatively coupled to the at least one clockconversion unit and configured to convert the plurality of downlinkasynchronous radio carrier signals to downlink analog intermediatefrequency signals; at least one switching unit communicatively coupledto the at least one intermediate frequency convertor and configured tocombine at least two of the plurality of downlink analog intermediatefrequency signals into an aggregate downlink analog intermediatefrequency signal; at least one radio frequency converter communicativelycoupled to the at least one intermediate frequency converter andconfigured to convert the aggregate downlink analog intermediatefrequency signal into a downlink radio frequency signal; at least oneantenna communicatively coupled to the at least one radio frequencyconverter and configured to wireless transmit the downlink radiofrequency signals to at least one subscriber unit.

Example 59 includes the remote antenna unit of Example 58, wherein theat least one clock conversion unit includes at least one resamplingfilter that re-clocks the plurality of downlink asynchronous radiocarrier signals to the master clock of the remote antenna unit from eachdifferent clock of each of the plurality of downlink asynchronous radiocarrier signal.

Example 60 includes the remote antenna unit of any of Examples 58-59,wherein the at least one clock conversion unit converts from a firstclock domain of an external device to a second clock domain of theremote antenna unit using a Farrow structure.

Example 61 includes the remote antenna unit of any of Examples 58-60,wherein the at least one clock conversion unit is configured to re-clockthe plurality of downlink asynchronous radio carrier signals byconverting first samples of a channelized radio carrier synchronous witha first clock of a first clock domain to second samples synchronous witha second clock of a second clock domain.

Example 62 includes the remote antenna unit of any of Examples 58-61,wherein the each of the plurality of downlink asynchronous radio carriersignals is specific to a particular channel and requires additionalbaseband conversion before radio frequency conversion and transmissioncan be performed; and wherein the aggregate downlink analog intermediatefrequency signal is not specific to a particular channel and does notrequire additional baseband conversion before radio frequency conversionand transmission can be performed.

Example 63 includes the remote antenna unit of any of Examples 58-62,wherein each of the downlink asynchronous radio carrier signals includesI/Q pairs.

Example 64 includes the remote antenna unit of any of Examples 58-63,wherein individual channels within the at least two of the plurality ofdownlink analog intermediate frequency signals do not overlap and can beupconverted together simultaneously to radio frequency spectrum oncecombined into the aggregate downlink analog intermediate frequencysignal.

Example 65 includes the remote antenna unit of any of Examples 58-64,wherein at least one of the plurality of external devices is at leastone of a host signal interface and an intermediary device.

Example 66 includes the remote antenna unit of any of Examples 58-65,wherein at least one of the downlink asynchronous radio carrier signalcontains a digital representation of a radio carrier positioned within aset of spectrum that reflects its eventual location within radiofrequency spectrum.

Example 67 includes the remote antenna unit of any of Examples 58-66,further comprising: wherein the at least one clock conversion unit isfurther configured to convert a plurality of uplink digitized radiofrequency signals to uplink asynchronous radio carrier signals at leastin part by re-clocking a plurality of uplink digitized radio frequencysignals to a plurality of asynchronous clocks, different from the masterclock of the remote antenna unit.

Example 68 includes the remote antenna unit of Example 67, whereindownlink and uplink signals within a radio frequency band are indistinct spectrum and are separated in frequency using a FrequencyDivision Duplexing (FDD) scheme.

Example 69 includes the remote antenna unit of any of Examples 67-68,wherein downlink and uplink signals within a radio frequency bandoverlap in spectrum and are separated in time using a Time DivisionDuplexing (TDD) scheme.

Example 70 includes a method for interfacing a plurality of asynchronousdownlink asynchronous radio carrier signal at an antenna unit,comprising: receiving a plurality of downlink asynchronous radio carriersignals for a plurality of radio frequency carriers from at least oneexternal device at the antenna unit, each of the plurality of downlinkasynchronous radio carrier signals having a different clock; re-clockingthe plurality of downlink asynchronous radio carrier signals to a masterclock of the antenna unit from each different clock of each of theplurality of downlink asynchronous radio carrier signals at the antennaunit; converting the plurality of downlink asynchronous radio carriersignals to downlink analog intermediate frequency signals at the antennaunit; combining at least two of the plurality of downlink analogintermediate frequency signals into an aggregate downlink analogintermediate frequency signal at the antenna unit; converting theaggregate downlink analog intermediate frequency signal into downlinkradio frequency signals at the antenna unit; wirelessly transmitting thedownlink radio frequency signals from the antenna unit to at least onesubscriber unit.

Example 71 includes the method of Example 70, wherein re-clocking theplurality of downlink asynchronous radio carrier signals to the masterclock of the antenna unit from each different clock of each of theplurality of downlink asynchronous radio carrier signals at the antennaunit occurs through a at least one resampling filter.

Example 72 includes the method of any of Examples 70-71, whereinre-clocking the plurality of downlink asynchronous radio carrier signalsto the master clock of the antenna unit converts the plurality ofdownlink asynchronous radio carrier signals from first clock domains ofthe plurality of channelized radio carrier signals to a second clockdomain of the antenna unit using a Farrow structure.

Example 73 includes the method of any of Examples 70-72, whereinre-clocking the plurality of downlink asynchronous radio carrier signalsto the master clock of the antenna unit includes converting firstsamples of a channelized radio carrier synchronous with a first clock ofa first clock domain to second samples synchronous with a second clockof a second clock domain.

Example 74 includes the method of any of Examples 70-73, wherein each ofthe plurality of downlink asynchronous radio carrier signals is specificto a particular channel and requires additional baseband conversionbefore radio frequency conversion and transmission can be performed; andwherein the aggregate downlink analog intermediate frequency signal isnot specific to a particular channel and does not require additionalbaseband conversion before radio frequency conversion and transmissioncan be performed.

Example 75 includes the method of any of Examples 70-74, wherein each ofthe downlink asynchronous radio carrier signal includes I/Q pairs.

Example 76 includes the method of any of Examples 70-75, whereinindividual channels within the at least two of the plurality of downlinkanalog intermediate frequency signals do not overlap and can beupconverted together simultaneously to radio frequency spectrum oncecombined into the aggregate downlink analog intermediate frequencysignal.

Example 77 includes the method of any of Examples 70-76, wherein atleast one of the plurality of external devices is at least one of a hostsignal interface and an intermediary device.

Example 78 includes the method of any of Examples 70-77, wherein atleast one of the downlink asynchronous radio carrier signal contains adigital representation of a radio carrier positioned within a set ofspectrum that reflects its eventual location within radio frequencyspectrum.

Example 79 includes the method of any of Examples 70-78, furthercomprising: converting a plurality of uplink digitized radio frequencysignals to uplink asynchronous radio carrier signals at the at least oneclock conversion unit at least in part by re-clocking a plurality ofuplink digitized radio frequency signals to a plurality of asynchronousclocks, different from the master clock of the remote antenna unit.

What is claimed is:
 1. A distributed antenna system, comprising: aplurality of signal interface circuits configured to receive a pluralityof downlink asynchronous radio carrier signals for a plurality of radiofrequency carriers from at least one external device, each of theplurality of downlink asynchronous radio carrier signals having adifferent clock; wherein the plurality of signal interface circuits isfurther configured to re-clock the plurality of downlink asynchronousradio carrier signals to a master clock of the distributed antennasystem from each different clock of each of the plurality of downlinkasynchronous radio carrier signals; wherein the plurality of signalinterface circuits is further configured to convert the re-clockedplurality of downlink asynchronous radio carrier signals to downlinkdigital signals; a host circuit communicatively coupled to the pluralityof signal interface circuits and configured to combine at least two ofthe downlink digital signals into an aggregate downlink digital signal;an antenna circuit communicatively coupled to the host circuit andconfigured to receive the aggregate downlink digital signal from thehost circuit; wherein the antenna circuit is further configured toconvert at least one of the aggregate downlink digital signal andanother signal based on the aggregate downlink digital signal intodownlink radio frequency signals; wherein the antenna circuit is furtherconfigured to wirelessly transmit the downlink radio frequency signalsto at least one subscriber unit.
 2. The distributed antenna system ofclaim 1, wherein the plurality of signal interface circuits includes atleast one resampling filter that re-clocks the plurality of downlinkasynchronous radio carrier signals to the master clock of thedistributed antenna system from each different clock of each of theplurality of downlink asynchronous radio carrier signals.
 3. Thedistributed antenna system of claim 1, wherein the at least one externaldevice includes a plurality of external devices, wherein the pluralityof signal interface circuits is configured to convert from first clockdomains of the plurality of external devices to a second clock domain ofthe antenna circuit using a Farrow structure.
 4. The distributed antennasystem of claim 1, wherein at least one of the plurality of signalinterface circuits is configured to re-clock at least one downlinkasynchronous radio carrier signal by converting first samples of achannelized radio carrier synchronous with a first clock of a firstclock domain to second samples synchronous with a second clock of asecond clock domain.
 5. The distributed antenna system of claim 1,wherein at least one of the plurality of downlink asynchronous radiocarrier signals is specific to a particular channel and requiresadditional baseband conversion before radio frequency conversion andtransmission is performed; and wherein the aggregate downlink digitalsignal is not specific to a particular channel and does not requireadditional baseband conversion before radio frequency conversion andtransmission is performed.
 6. The distributed antenna system of claim 1,wherein at least one of the downlink asynchronous radio carrier signalsincludes I/Q pairs.
 7. The distributed antenna system of claim 1,wherein individual channels within the at least two of the downlinkdigital signals do not overlap and are upconverted togethersimultaneously to radio frequency spectrum once combined into theaggregate downlink digital signal.
 8. The distributed antenna system ofclaim 1, wherein one or more of the at least one external device is abaseband processing unit of a base station.
 9. The distributed antennasystem of claim 1, wherein at least one of the plurality of downlinkasynchronous radio carrier signals received at the plurality of signalinterface circuits uses at least one of a Synchronous Optical Networking(SONET) protocol and an Ethernet protocol to receive I/Q pairs.
 10. Thedistributed antenna system of claim 1, wherein at least one of theplurality of signal interface circuits includes at least one of a CommonPublic Radio Interface (CPRI) base station interface, an Open BaseStation Architecture Initiative (OBSAI) base station interface, and anOpen Radio Interface (ORI) interface; and wherein at least one of theplurality of downlink asynchronous radio carrier signals is formattedaccording to at least one of a Common Public Radio Interface (CPRI)standard, an Open Base Station Architecture Initiative (OBSAI) standard,and an Open Radio Interface (ORI) standard.
 11. The distributed antennasystem of claim 1, wherein at least one of the plurality of downlinkasynchronous radio carrier signals contains a digital representation ofa radio carrier positioned within a set of spectrum that reflects theeventual location of the radio carrier within radio frequency spectrum.12. The distributed antenna system of claim 1, further comprising:wherein the plurality of signal interface circuits is further configuredto convert a plurality of uplink digital signals to uplink asynchronousradio carrier signals at least in part by re-clocking a plurality of theuplink digital signals to a plurality of asynchronous clocks, differentfrom the master clock of the distributed antenna system.
 13. A methodfor interfacing a plurality of asynchronous downlink asynchronous radiocarrier signals in a distributed antenna system, comprising: receiving aplurality of downlink asynchronous radio carrier signals for a pluralityof radio frequency carriers at a plurality of signal interface circuitsfrom at least one external device, each of the plurality of downlinkasynchronous radio carrier signals having a different clock; re-clockingthe plurality of downlink asynchronous radio carrier signals to a masterclock of the distributed antenna system from each different clock ofeach of the plurality of downlink asynchronous radio carrier signals atthe plurality of signal interface circuits; converting the re-clockedplurality of downlink asynchronous radio carrier signals to downlinkdigital signals at the plurality of signal interface circuits;communicating the downlink digital signals from the plurality of signalinterface circuits to a host circuit; combining at least two of thedownlink digital signals into an aggregate downlink digital signal atthe host circuit; communicating the aggregate downlink digital signalfrom the host circuit to an antenna circuit; and converting at least oneof the aggregate downlink digital signal and another signal based on theaggregate downlink digital signal into downlink radio frequency signalsat the antenna circuit.
 14. The method of claim 13, further comprising:wirelessly transmitting the downlink radio frequency signals to at leastone subscriber unit.
 15. The method of claim 13, wherein re-clocking theplurality of downlink asynchronous radio carrier signals to the masterclock of the distributed antenna system from each different clock ofeach of the plurality of downlink asynchronous radio carrier signals atthe antenna circuit occurs through at least one resampling filter. 16.The method of claim 13, wherein the at least one external deviceincludes a plurality of external devices, wherein re-clocking theplurality of downlink asynchronous radio carrier signals to the masterclock of the distributed antenna system converts the plurality ofdownlink asynchronous radio carrier signals from first clock domains ofthe plurality of external devices to a second clock domain of theantenna circuit using a Farrow structure.
 17. The method of claim 13,wherein re-clocking the plurality of downlink asynchronous radio carriersignals to the master clock of the distributed antenna system includesconverting first samples of a channelized radio carrier synchronous witha first clock of a first clock domain to second samples synchronous witha second clock of a second clock domain.
 18. The method of claim 13,wherein each of the plurality of downlink asynchronous radio carriersignals is specific to a particular channel and requires additionalbaseband conversion before radio frequency conversion and transmissionis performed; and wherein the aggregate downlink digital signal is notspecific to a particular channel and does not require additionalbaseband conversion before radio frequency conversion and transmissionis performed.
 19. The method of claim 13, wherein each of the downlinkasynchronous radio carrier signals includes I/Q pairs.
 20. The method ofclaim 13, wherein individual channels within the at least two of theplurality of downlink digital signals do not overlap and are upconvertedtogether simultaneously to radio frequency spectrum once combined intothe aggregate downlink digital signal.
 21. The method of claim 13,wherein one or more of the at least one external device is at least oneof a baseband processing unit of a base station.
 22. The method of claim13, wherein receiving at least one of the plurality of downlinkasynchronous radio carrier signals for the plurality of radio frequencycarriers occurs using at least one of a Synchronous Optical Networking(SONET) protocol and an Ethernet protocol to transmit I/Q pairs.
 23. Themethod of claim 13, wherein at least one of the plurality of signalinterface circuits includes at least one of a Common Public RadioInterface (CPRI) base station interface, an Open Base StationArchitecture Initiative (OBSAI) base station interface, and an OpenRadio Interface (ORI) interface; and wherein at least one of theplurality of downlink asynchronous radio carrier signals is formattedaccording to at least one of a Common Public Radio Interface (CPRI)standard, an Open Base Station Architecture Initiative (OBSAI) standard,and an Open Radio Interface (ORI) standard.
 24. The method of claim 13,wherein at least one of the plurality of downlink asynchronous radiocarrier signals contains a digital representation of a radio carrierpositioned within a set of spectrum that reflects the eventual locationof the radio carrier within radio frequency spectrum.
 25. The method ofclaim 13, further comprising: converting a plurality of uplink digitalsignals to uplink asynchronous radio carrier signals at the plurality ofsignal interface circuits at least in part by re-clocking a plurality ofthe uplink digital signals to a plurality of asynchronous clocks,different from the master clock of the distributed antenna system.